









































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































* 




















I 






















ANIMAL ACTIVITIES 





























ANIMAL ACTIVITIES 


A FIRST BOOK IN ZOOLOGY 


BY 

NATHANIEL S. FRENCH, Ph.D. 

it ’ 

Teacher of Zoology in the Roxbury High School 
Boston , Mass. 


HCUtb ITllustrattons 


NEW IMPRESSION 


LONGMANS, GREEN, AND CO. 

91 AND 93 FIFTH AVENUE, NEW YORK 
LONDON AND BOMBAY 

1905 




Copyright, 1901, 

BY 

LONGMANS, GREEN, AND CO. 

First Edition, March, 1902; 
Reprinted, January, 1903. 
Reprinted, August, 1905. 


Transfer 

( c < 

Engineers <S ( ohoof l^iby, 
June 29 ,. 9 . 


ROBERT DRUMMOND, PRINTER, NEW YORK. 



INTRODUCTION. 


The book here presented is the outgrowth of fifteen 
years of teaching the subject to large classes in a high 
school. Its aim is to interest and guide pupils in the 
study of living animals. Young people are usually 
ready to be made acquainted with their immediate 
neighbors in the animal world, and it is hoped that 
this book may be of assistance to them. 

In the choice and arrangement of topics the powers 
and interests of young students have been kept in view 
rather than the demands of strictly logical description 
and exposition. Chapter I outlines the animal kingdom 
in such a manner as to be useful for reference purposes. 
Chapter II gives directions for assisting the student in 
procuring his own specimens for study. Chapter III 
describes the activities common to all animals. With 
Chapter IV work on the Arthropoda begins. Animals 
of this group are selected for the early part of the work 
because living specimens can be easily collected and 
observed in the fall, at which time Zoology is begun 
in most schools. After the study of the Arthropoda, 
the book follows the natural order, beginning with the 
simplest animals and ending with the most complex. 
In some schools it will doubtless be better to begin 
with Chapter XI, and study the Arthropoda directly 
after the chapter on “ The Earthworm ”. This latter 
order of subjects is advised when the Zoology course 
begins in the winter or spring. 

Throughout the book adaptation to environment is 
constantly pointed out. Much is made of habitat in 


VI 


INTRODUCTION. 


connection with the manner in which an animal per¬ 
forms its life-functions. 

The directions for laboratory work are mainly in the 
form of questions which must be answered from direct 
observation. Comparisons and inferences are con¬ 
stantly required of the pupil. The exercises for review 
of note-book work enable pupils to systematize their 
knowledge. Useful vocabularies are frequently in¬ 
serted. 

For many valuable suggestions the author is in¬ 
debted to Miss Helen A. Gardner and Miss Mary E. 
Winn of the Girls’ High School, Boston, and Prof. B. 
H. Van Vleck of Boston University, who read the 
manuscript; and to Mr. Frank M. Whitney, principal 
of the Watertown, Mass., High School and Miss E. O. 
Patch of the Girls’ High School, Boston, who ex¬ 
amined the proof-sheets. Mr. Lyman G. Smith of the 
Roxbury High School and Mr. Arthur E. Sanford 
assisted in preparing some of the drawings, and many 
of the illustrations have been reproduced, by per¬ 
mission, from Agassiz’s “ Seaside Studies ” (Houghton, 
Mifflin, & Co.), “The Horse” by W. H. Flower 
(D. Appleton & Co.), various works published by 
Longmans, Green, & Co., and other sources. 

A LIST OF BOOKS. 

All the books on the list given below have been 
found useful to pupils, and nearly all of them have been 
reported as ‘ ‘ interesting ’ ’ by many pupils who have 
read them. Such books may be used to advantage in 
the preparation of Reports. The list was first printed 
by a branch of the Agassiz Society connected with the 
Roxbury High School of Boston, Mass. 

Abbott, Charles Conrad : 

A Naturalist’s Rambles about Home. 

Bird Land Echoes. Illustrated. 

Agassiz, Elizabeth and Alexander: 

Seaside Studies in Natural History. Illustrated. 


INTRODUCTION . 


Vll 


Allen, Grant : 

Flashlights on Nature. Illustrated. 

Apgar, Austin C. : 

Birds of the United States. Illustrated. 

Badenoch, L. N. : 

Romance of the Insect World. Illustrated. 
Bausch, Edward: 

Manipulation of the Microscope. 

Bateman, G. C. : 

The Vivarium. Illustrated. 

Beard, James Carter: 

Curious Homes and their Tenants. Illustrated. 
Beddard, Frank E. : 

Elementary Practical Zoology. 

A Text-book of Zoogeography. 

Bolles, Frank: 

At the North of Bearcamp Water. 

Brooks, W. K. : 

The Oyster. Illustrated. 

Buckley, Arabella B. : 

Life and her Children. Illustrated. 

The Winners in Life’s Race. Illustrated. 

Burroughs, John: 

Birds and Bees and Sharp Eyes. 

Riverby. 

Wake Robin. 

Locusts and Wild Honey. 

Carrington, Edith: 

Animals’ Ways and Claims. Illustrated. 

Chapman, Frank M.: 

Bird Life. Illustrated. 

Chatty Readings in Elementary Science (Longmans): 
Nature Knowledge, Books I, II, III. Illustrated. 

Cornish, C. J. : 

Animals of To-day. Illustrated. 

Animals at Work and Play. Illustrated. 

Wild Animals in Captivity. Illustrated. 


INTRODUCTION. 


viii 

Corey, C. B. : 

How to Know the Shore Birds. Illustrated. 

Darwin, Charles R. : 

What Mr. Darwin saw in his Voyage Round the World 
in the Ship “ Beagle ”. Illustrated. 

The Formation of Vegetable Mould. Illustrated. 
Davie, Oliver: 

Nests and Eggs of North American Birds. Illustrated. 
De Kay, Charles : 

Bird Gods. Illustrated. 

Dixon, Charles: 

Curiosities in Bird Life. 

Doubleday, N. B. DeG. : 

Birds that Hunt and are Hunted. Illustrated. 

Bird Neighbors. Illustrated. 

Duncan, P. Martin: 

The Transformation of Insects. Illustrated. 

Davenport, C. B. and G. C.: 

Introduction to Zoology. Illustrated. 

Edwards, Clarence E. : 

The Campfires of a Naturalist. Illustrated. 

Emerton, J. H. : 

The Structure and Habits of Spiders. Illustrated. 
Figuier, Guillaume Louis: 

The Ocean World. Illustrated. 

The Insect World. Illustrated. 

Flower, William Henry: 

The Horse. Illustrated. 

Forbes, Edward: 

A History of British Starfishes. Illustrated. 

French, G. H. : 

The Butterflies of the Eastern United States. 

Furneaux, W. : 

The Out-door World. Illustrated. 

Life in Ponds and Streams. Illustrated. 

Graham, P. Anderson : 

Country Pastimes for Boys. Illustrated. 

Holland, W. J.: 

The Butterfly Book. Illustrated. 


INTRODUCTION. 


ix 


Jordan and Kellogg: 

Animal Life. Illustrated. 

Kearton, R.: 

Wild Life at Home. How to Study and Photograph it. 
Illustrated. 

Kingsley, John Sterling: 

The Riverside Natural History, five volumes. Illus¬ 
trated. 

Lovell, M. S. : 

Edible Mollusks of Great Britain. 

Lubbock, Sir John: 

On the Origin and Metamorphosis of Insects. 

The Beauties of Nature and Wonders of the World. 
Ants, Bees, and Wasps. Illustrated. 

Mangin, Arthur: 

The Mysteries of the Ocean. Illustrated. 

Manton, Walter P. : 

Taxidermy without a Teacher. 

Insects, How to Catch and Prepare. 

Mathews, F. Schuyler: 

Familiar Life in Field and Forest. Illustrated. 
McCook, Henry C. : 

The Honey Ants of the Garden of the Gods. Illustrated. 
Merriam, Florence A.: 

Birds of Field and Village. Illustrated. 

Birds Through an Opera Glass. Illustrated. 

Merriam, C. Hart: 

Mammals of the Adirondack Region. 

Miall, Louis Compton: 

The Natural History of Aquatic Insects. Illustrated. 
Round the Year. Illustrated. 

Michelet, Jules: 

The Insect. Illustrated. 

The Bird. Illustrated. 

Miller, Olive Thorne: 

Little Brothers of the Air. 

Four-handed Folk. Illustrated. 

Bird Ways. 

In Nesting Time. 

Little Folks in Feathers and Fur. Illustrated. 


X 


INTRODUCTION. 


Morgan, C. L. : 

Animal Sketches. Illustrated. 

Needham, James G. : 

Outdoor Studies. Illustrated. 

Nehrling, Henry: 

Native Birds of Song and Beauty. Illustrated, two 
volumes. 

Oswald, Felix L. : 

Zoological Sketches. Illustrated. 

Packard, A. S.: 

A Guide to the Study of Insects. Illustrated. 

Parkhurst, H. E.: 

The Birds’ Calendar. Illustrated. 

Porter, J. Hampden: 

Wild Beasts. Illustrated. 

Russ, Karl: 

The Speaking Parrots. Illustrated. 

Scudder, Samuel H. : 

The Life of a Butterfly. Illustrated. 

Butterflies: Structure, Changes, and Life-histories. 
Semper, Frank W. : 

Injurious Insects, and Use of Insecticides. Illustrated. 
Shaler, Nathaniel S. : 

Domesticated Animals. Illustrated. 

Simmonds, P. L. : 

Commercial Products of the Sea. Illustrated. 

Stokes, A. C. : 

Microscope for Beginners. 

Thomson, William: 

Great Cats I Have Known. Illustrated. 

Thompson, Ernest Seton: 

Wild Animals I Have Known. Illustrated. 

Torrey, Bradford : 

Birds in the Bush. 

Wallace, Alfred Russell: 

Darwinism. Illustrated. 

Weed, Clarence Moore: 

Life-histories of American Insects. Illustrated. 


INTRODUCTION. 


xi 


Wilson, Sir Daniel: 

Left-handedness. 

Wood, Theodore: 

The Farmers’ Friends and Foes. Illustrated. 

Wood, Rev. J. G.: 

Homes Without Hands. Illustrated. 

Wright, Mabel Osgood: 

Four-footed Americans. Illustrated. 

Bird Craft. Illustrated. 



TABLE OF CONTENTS. 

PAGE 

Introduction . vii 

CHAPTER I. 

Animals Classified. £ 

CHAPTER II. 

Material for Study. 4 

CHAPTER III. 

Activities Common to All Animals. ...^. 24 

CHAPTER IV. 

Grasshoppers and Crickets. 32 

CHAPTER V. 

Butterflies and Moths with their Protective Devices... 45 

CHAPTER VI. 

Some Insects Classified. 57 

CHAPTER VII. 

A Chapter of Life-Histories. 68 

xiii 









xiv TABLE OF CONTENTS. 

CHAPTER VIII. 

Some Insect Adaptations. 

CHAPTER IX. 


A Spider’s Activities, 


CHAPTER X. 

Homologies among Crustacea. 

CHAPTER XI. 

The Activities of One-Celled Animals and Sponges. 

CHAPTER XII. 

The Hydra and Some Ccelenterates which Live in Colonies 

CHAPTER XIII. 

The Starfish and Closely Related Animals. 

CHAPTER XIV. 

The Earthworm and His Work. 

CHAPTER XV. 


Mussels and Snails, 


CHAPTER XVI. 

The Structure and Activities of a Fish. 

CHAPTER XVII. 


PAGE 

86 


93 


IOI 


116 


128 


140 


148 


155 


169 


Tadpoles and Frogs 


179 











TABLE OF CONTENTS. 


xv 


CHAPTER XVIII. 

PAGE 

Birds. 197 

CHAPTER XIX. 

Man’s Near Relatives. 2.11 

CHAPTER XX. 

The Distribution of Animals. 236 

CHAPTER XXL 


Animal Relationships 


243 







LIST OF ILLUSTRATIONS. 


FIG. 


2 . 

3- 

4 - 

5- 

6 . 

7- 

8 . 

9- 

10. 

11. 

12 . 
13- 
14. 
!5- 
16. 

*7- 

18. 


19. 

20. 

21. 

22. 


23- 

24. 

25 - 

26. 

27. 

28. 

29. 

30. 

3 1 - 

32. 

33- 

34- 
35 
3 6 - 


37- 


38 . 


39 - 


Note. — The figures in brackets [il following the titles re¬ 
fer to the list, printed below, of books from which the 
illustrations are, by permission, respectively borrowed. 


An Insect-net. 

The House-cricket [1]. 

A Cabbage-butterfly. 

Spider and Web. 

A Water-snail. 

Shell of a Fresh-water Mussel [2]. 

An American Pondweed. 

The Hornwort. 

A Duckweed. 

Other Pond weeds.. 

The Hydra [ 2 ] . 

Water-fleas and Cyclops. 

Caddis-fly Cases (2]. 

The Larva of Dragon-fly. 

Larva of Dyticus. 

Larva of Whirligig Beetle. 

Larva of a May-fly. 

Side View of Crayfish [5]. 

A Campanularian Hydroid Colony [6]. 

A Sertularian Colony [6]. 

A Net for Collecting at the Seaside. 

Sea-anemones. 

A Starfish [6]. 

A Sea-urchin. 

A Sea-cucumber. 

A Hermit-crab. 

A Shrimp. 

Tumbler with Chloroform. 

A Cockroach [1]. 

Mourning-cloak Butterfly. 

A Wasp’s Nest [3]. 

Cocoon of Cecropia. 

Eggs of Frog Just Laid [2]. 

Eggs of Frog a Few Hours After Laying [2]. 

Apparatus for Decomposing Water.. 

Apparatus for Removing Oxygen from Air. 

Heating a Test-tube.. 

The Parts of a Locust .. 

Comparison of a Grasshopper and Man..... 

xvii 


PAGE 


4 

5 

6 

7 

8 
8 
9 
9 
9 

10 

10 

11 

12 
12 
12 
12 

12 

13 

14 

15 

15 

16 

17 

17 

18 
18 

18 

19 

20 

21 

22 

22 

23 
23 

26 

28 

28 


35 


36 









































xviii 


LIST OF ILLUSTRATIONS. 


FIG. 

40. The Trachea of an Insect [2]. 

41. Cockroach and Cast Skin [1]. 

42. The Nervous Chain of a Cockroach [1]. 

43. Portion of the Cornea of a Fly’s Compound Eye [1] 

44. The Hearing Organ of a Cricket [1]. 

45. The Stridulating Organ of a Cricket [1]. 

46. Antennae of Lepidoptera [4]. 

47. Eggs of Lepidoptera [4]. 

48. Some Larvae of Lepidoptera. 

49. Some Cocoons and Chrysalids [4]. 

50. A Cabbage-butterfly. 

51. Head of a Moth. 

52. The Kallima. 

53. Catocala Nupta [4]. 

54. The Milkweed-butterfly. 

55. Limenitis Ursula. 

56a. Moth at Rest. 

56A Butterfly at Rest. 

57. Larva and Pupa of the House-fly [1]. 

58. Right Winglet of Bluebottle [1]. 

59. Balancer of Bluebottle [1]. 

60. Portion of a Fly’s Foot [1]. 

61. Side View of Proboscis, partly opened [1]. 

62. Head of Bluebottle [1]. 

63. Eggs of Milkweed-butterfly. 

64. Larva of Milkweed-butterfly. 

65. Pupa of Milkweed-butterfly. 

66. Female and Male Aphis. 

67. A Microgaster Fly. 

68. The Dragon-fly [2]. 

69. The Imago of a Dragon-fly [2]. 

70. Caddis-fly, Adult and Larval Cases [2]. 

71. The Growth of a May-fly [2]. 

72. A Water-boatman. 

73. Dyticus Marginalis. 

74. Mouth of a Bug. 

75. The Egg-raft of a Mosquito [3]. 

76. The Life-history of a Mosquito. 

77. The Mouth of a Female Mosquito [2J. 

78. The Leg of a Cockroach [1]. 

79. A Mole-cricket. 

80. Fore Legs of a Water-bug [2]. 

81. Legs of Dyticus [2]. 

82. Fore Leg of a Butterfly [4]. 

83. Ilive-bees. 

84. Fertilization of a Flower by an Insect. 

85. A Spider’s Leg [2]. 

86. Water-spider and Nest. 

87. Side View of Crayfish [5]. 

88. Dorsal View of Crayfish [5]. 

89. Ventral View of Crayfish [5]. 


PAGE 

38 

39 

40 

41 

41 

42 

46 

47 

48 
48 


49 

50 

5 1 

52 

53 
53 
55 
55 


58 

58 

58 


59 

59 


69 

69 

7 i 

75 

77 


78 


79 

80 

81 

81 

82 

82 

83 

84 


86 

86 


87 

87 

88 


90 

9 1 
94 
96 

101 

102 

103 





















































LIST OF ILLUSTRATIONS. 


xix 


FIG. 


PAGK 


90. Fourth Abdominal Segment of Crayfish [5]. 

91. Crayfish Appendages [5]. 

92. Longitudinal Section of Crayfish [5]. 

93. Walking Appendage of Crayfish with Gill Attached [5]. 

94. The Common Crab. 

95. Early Stages of Shore-crab. 

96. Water-flea [2]. 

97. Cyclops [2]. 

98. A Barnacle. 

99. Forms of Amoebae. 

100. Amoeba Feeding [2]. 

ior. Amoeba Dividing [2]. 

102. One of the Foraminifera. 

103. The Origin of Chalk. 

104. Infusorial Earth. 

105. Infusorians. 

106. Vorticella [8]. 

107. A Paramecium [5]. 

108. Structure of a Sponge. 

109. Sponge Spicules [2]. 

no. Thread-cells [2]. 

in. Forms of Hydra [8]. 

112. Hydractinia [6]. 

113. Medusae of Campanularian Hydroid [6]. 

114. The Origin of a Scyphozoan Jelly-fish. 

115. The Structure of a Sea-anemone. 

116. A Starfish. 

117. A Brittle Starfish. 

118. The Structure of a Sea-urchin. 

119. A Sea-cucumber. 

120. An Earthworm. 

121. A Worm’s Setae. 

122. Worm-casts. 

123. A Fresh-water Mussel Showing Position of Foot and Siphons.. 

124. Fresh-water Mussel with One Valve Removed [5]. 

125. Digestive Tube of Fresh-water Mussel [5]. 

126. Cross-section of Anodon [5]. 

127. Nervous System of Anodon [5]. 

128. A Slug. 

129. A Snail. 

130. A Squid. 

131. Part of a Lingual Ribbon. 

132. The Circulation of Blood in a Fish. 

133. Internal Organs of Fish. 

134. Skeleton of a Fish.;. 

135. Tongue of a Frog. 

136. A Young Tadpole Showing External Giils [2]. 

137. Under Side of Tadpole Showing Coiled Intestine and Internal 

Gills [2]. 

138. Heart of Adult Frog [2]. 

139. Blood-cells of a Frog [9]. 


104 

10 5 

106 

107 

108 

108 

109 
109 
no 

117 

118 

119 

120 

120 

121 

121 

122 

123 

124 

125 

130 

131 

132 

134 

135 

136 
142 
144 
146 
146 


149 

150 
150 

157 

159 

160 

161 
161 
163 

165 

166 
166 

171 

172 

173 
182 
182 


183 

183 

183 



















































XX 


LIST OF ILLUSTRATIONS . 


FIG. 

140. Blood-corpuscles of Man [9].. 

141. Viscera of Frog. 

142. Digestive Organs of Man [9]. 

143. Growth of Frog’s Lung from Primitive Food-tube. . 

144. Growth of Frog’s Egg [2]. 

145. Very Young Tadpoles [2]. 

146. Various Stages of Tadpole [2]. 

147. Young Frogs [2]. 

148. The Use of a Muscle. 

149. Striped Muscle-fibres [9]. 

150. Unstriped Muscle fibres [9]. 

151. A Frog’s Skeleton. 

152. A Man’s Skeleton. 

153. Brain of Frog. 

154. Brain and Spinal Cord of Man. 

155. Beaks of Various Birds. 

156. The Digestive Organs of a Bird. 

157. Diagram of the Heart of a Bird [3]. 

158. The Skeleton of a Bird. 

159. A Swallow Feeding Her Young. 

160. Arm of Man, Fore Leg of Dog, Wing of Bird. 

161. A Bird’s Wing. 

162. The Sternum of a Shrike..*. 

163. Feathers. 

164. A Bird’s Leg. 

165. Feet of Birds. 

166. The Archaeopteryx. 

167. Teeth of Man [g]. 

168. Teeth of Dog. 

169. Teeth of a Sheep [3]. 

170. Teeth of Hare. 

171. Skull of Cow Showing Teeth. 

172. The Human Eye. 

173. Skeletons of Man and Horse [10]. 

174. Bones of Leg and Arm of Man [11]. 

175. Vertebral Column of Man [11]. 

176. Human Skull [11]. 

177. First and Second Vertebrae of Man [9]. 

178. Skeleton of Gorilla. 

179. Diagram Showing Circulation of Blood in Man [n] 

180. Skeleton of Bat Showing Wings. 

181. Arm and Hand of Man [11]. 

182. Skeleton of Chimpanzee Showing Hand. 

183. Fore Foot of Mole. 

184. Fore Foot of Cat. 

185. Fore Feet of Cow. 

186. Fore Feet of Horse. 

187. Foot of Elephant. 

188. Feet of Bear. 

189. Sole of Foot of Man, of Dog, and of Horse [10].. . . 

190. Finger of Man and of Horse [10]. 


PAGE 

I84 


187 

188 
188 
189 

189 

190 

1 9 1 

192 

193 

194 

194 

195 

199 

200 
201 
202 

203 

204 
204 
205 
206 
207 
208 
209 
212 
212 

213 
213 

214 
214 

215 

216 
216 

217 

219 

220 
221 
222 
222 

223 

224 
224 
225 
225 
225 
22C 
226 
227 





















































LIST OF ILLUSTRATIONS. 


xxi 


PIG. PAGE 

191. Feet of Ancestors of Horse. 228 

192. Growth of Hair [9]. 229 

193. Horns of Sheep, Cow, and Deer. 230 

194. Skull of Cow Showing the Bone of the Horn. 231 

195. A Manlike Ape Walking. 232 

196. A Chimpanzee. 233 

197. Feet of Ancestors of Horse. 244 

198. A Pterodactyl. 245 

199. The Archaeopteryx. 246 

200. Diagram of a Sea-squirt. 247 

201. Amphioxus. 247 

202. Growth of Frog’s Lung from Primitive Food-tube. 248 

203. Morula Stage [7] . 249 

204. Gastrula Stage [7]. 249 

205. A Genealogical Tree [7].252 


1. Our Household Insects. E. A. Butler, Longmans, Green, & Co. 

2. Life in Ponds and 

Streams. ByW. Furneaux , “ “ “ 

3. The Outdoor World. . .ByW. Furneaux, “ “ 

4. Butterflies and Moths.^ W. Furneaux, “ “ “ 

5. Practical Elementary 

Biology. By John Bidgood, “ “ “ 

6. Seaside Studies in Natu¬ 

ral History. .. .By £. and A. Agassiz, Houghton, Mifflin, &Co. 

7. The Story of Creation. Edw. Clodd, Longmans, Green, & Co. 

8. Animal Biology. By C. L . Morgan, “ “ “ 

9. Quain’s Anatomy, 10th Edition. “ “ 

10. The Horse . By W.H. Flower, D. Appleton & Co. 

11. Human Physiology. ByW. Furneaux, Longmans, Green, & Co. 





























ANIMAL ACTIVITIES. 


CHAPTER I. 

ANIMALS CLASSIFIED. 

IN the course of these lessons on Animal Activities 
the student will be called on to observe many forms of 
animal life and to learn many new and perhaps strange 
names. In order that he may keep his bearings and 
feel somewhat at home from the start, the following 
classification of the animal kingdom is given. The 
student should read over this table carefully, noting 
especially the meaning of the names in the light of 
their derivation, and he should refer to it frequently. 
Later in the book more will be said about classification. 

The animal kingdom is divided by zoologists into 
subkingdoms. As these subkingdoms are supposed 
to consist of animals related through their ancestry, 
they are sometimes called phyla ( phylum , a tribe). 
Since Zoology is a rapidly growing science, authorities 
differ in regard to tne number of divisions, or phyla, 
and also in regard to the names for some of the 
divisions. 



2 


ANIMAL ACTIVITIES. 


Phylum 
or Sub¬ 
kingdom. 

Name of Sub- 
kingdom. 

Derivation of 
Name. 

A Few Characteristics. 

Familiar Examples 

I. 

Pro to zo'a. 

Gr. protos, 
first, and 
zoon, ani¬ 
mal. 

One-celled ani¬ 
mals. 

They do not re¬ 
produce by eggs. 

Amoeba, para- 
mecium, vor- 
ticella, chalk 
animals. 

II. 

Po rif'e ra. 

Lat. porus , 
a pore, and 
fero, to bear 

Animals having 
many cells 
much alike. 
Food enters the 
body by numer¬ 
ous openings. 

All sponges. 

III. 

Cge len te- 
ra'ta. 

Gr. koilos, 
hollow, and 
enteron , in¬ 
testine. 

Animals having 
hollow cylindri¬ 
cal bodies with 
only one open¬ 
ing, the mouth. 

Hydras, hy- 
droids, jelly¬ 
fish, corals, 
sea-anemones 

IV. 

E CHI NO- 
der'ma ta. 

Gr. echinos , 
a hedgehog, 
and derma , 
skin. 

Animals having 
very distinct ra¬ 
dial symmetry, 
having hard 
plates in the 
skin, and fre¬ 
quently covered 
by spines. 

Starfish, sea- 
urchins, sea- 
cucumbers, 
and stone- 
lilies. 

V. 

Ver'mes. 

Lat. vermis , 
a worm. 

Include a great 
variety of worm¬ 
like animals. 
Some have seg¬ 
mented bodies. 

Earthworms, 

leeches. 

VI. 

Ar throp'o- 

DA. 

Gr. arihron, 
a joint, and 
pous (pod), 
a foot. 

Animals having 
segmented bod¬ 
ies and jointed 
appendages. 

Grasshoppers, 
butterflies, 
spiders, cray¬ 
fish, crabs, 
centipedes. 

VII. 

Mol lus'ca. 

Lat. mollis, 
soft. 

Soft-bodied ani¬ 
mals, often en¬ 
closed in hard 
shells. 

Clams, snails, 
the nautilus, 
and the squid. 

VIII. 

Chor da'ta. 

Gr. chorde , 
a string. 

Almost all have 
back bones 
made up of parts 
called vertebrae. 

Fishes, frogs, 
turtles, 
snakes, birds, 
horses, and 
man. 



















ANIMALS CLASSIFIED 


3 


In the following pages directions are given for the 
laboratory study of the activities, as well as of the 
structure of the animals mentioned below. 

A paramecium, belonging to Protozoa. 

A sponge, belonging to Porifera. 

A hydra and a hydroid colony , belonging to Ccelen- 
terata. 

A starfish and a sea-urchin, belonging to Echino- 
dermata. 

An earthworm, belonging to Vermes. 

A grasshopper, a butterfly, a house-fly, a potato- 
beetle, a spider, a centipede, and a crayfish or a lobster, 

belonging to Arthropoda. 

A mussel, a slug, and a snail, belonging to Mollusca. 

A fish, a frog, and a belonging to Chordata. 

Directions for a short study of some domestic animals 
related to man are also given. 


CHAPTER II. 


MATERIAL FOR STUDY. 

In order to study the activities of animals it is neces¬ 
sary (i) to have apparatus, (2) to collect many forms 
of animal life and provide suitable conditions for them, 
and (3) to prepare and preserve specimens. All work 
of this kind can best be done by the members of the 
class. It is a good plan for small groups of volunteers 
to assume responsibility for carrying out the directions 
of the several paragraphs which follow. 

APPARATUS AND REFERENCE BOOKS. 

Not much apparatus is needed. A net for collecting 
insects may be made by bending a piece of telegraph- 
wire into the shape indicated in Fig. 1, fastening it to 



Fig. 1. — An Insect-net. Drawn by A. E. Sanford. 

a pole, and sewing it into a bag made of mosquito¬ 
netting. For water collecting, a tin strainer attached 
to a wooden handle answers admirably. Fruit-jars and 
jelly-tumblers with tin covers make good collecting 
vessels. A few books should be at hand for reference. 
Bulletin No. 39, U. S. National Museum, can be had 


4 





MATERIAL FOR STUDY . 


5 


by sending to the National Museum in Washington. 
It contains valuable directions for collecting and pre¬ 
serving animals, and no school need be without it. 
“The Out-door World ”, Furneaux, (Longmans,) is 
a useful help in this work. 

Write your name plainly on a label affixed to the 
jar or other vessel in which you have placed your col¬ 
lections. Write a brief statement telling where and 
under what circumstances your specimens have been 
collected. Hand jar and statement to the teacher at 
the same time. 


LIVING MATERIAL FOR FALL USE. 

Grasshoppers and Crickets. Collect these insects 
and place them in tumblers, or similar glass vessels, 
covered with netting. Put earth 
in the bottom of each tumbler and 
keep it moist. Feed the insects 
with lettuce, or similar vegetable 
food. Watch the movements of 
male crickets while chirping. 

Female crickets may often be seen 
depositing eggs. The females 
may be recognized by the long, 
slender, egg-depositing organs at 
the end of the abdomen. Use 
these specimens with the directions 
in Chapter IV. Grasshoppers and 
crickets may be fed on bread. 

Wasps and Butterflies. Place 
wasps in tumblers in a similar 
manner, and feed them on sugar Pig. 2.— The House- 
and water. Try, also, butterflies 

and moths in the same way, using larger glass vessels. 
If eggs are deposited, examine them carefully and 
watch their growth. 



6 


ANIMAL ACTIVITIES. 


Caterpillars. Keep these singly in tumblers with 
fresh supplies of the plant on which they are found 
feeding. When many caterpillars are needed for class 


study a “ breeding-cage 


may be made by placing 
earth in the bottom of a 
large box, covering the 
box with netting, and 
supplying plenty of food 
and moisture. If panes 
of glass can be set in the 
sides of the box, so much 
the better. Cabbage- 
worms are easily ob¬ 
tained, and the butterflies 
can be reared from them 
with very little care. The 
cabbage - butterflies are 
sometimes called 
“whites”. In observ¬ 
ing butterflies and cater¬ 
pillars use the questions 
in Chapter V. 

Flies. Allow adult 
bluebottle flies to deposit 
eggs on pieces of meat or 
fish in tumblers. Watch 
the growth of the eggs. 
Keep in a fairly warm 
place and furnish mois- 
See further suggestions in Chapter VI. House¬ 
flies may be watched in tumblers. Feed them on 
sugar and watch their movements. Early in the 
fall house-flies will deposit their eggs on stable- 
manure. 

Spiders. All our common spiders are harmless. 
To collect spiders invert a tumbler over them, and im¬ 
prison the insects by covering the mouth of the tumbler 
with a card. The garden-spider is a good one to 



—A Cabbage-butterfly. < 
b, pupa; c, egg; d, imago. 


ture. 






MATERIAL FOR STUDY. 


7 


observe. Provide flies and other small insects for food, 
and watch the web-making, the feeding, and other 
activities. Further questions 
and suggestions will be found 
in Chapter IX. 

Earthworms. Fill one or 
two large battery-jars with 
moist earth and decaying 
leaves and put in each jar 
several earthworms. Cover 
the jars and keep the earth 
well moistened. Keep all 
winter. Watch in connec¬ 
tion with directions in Chap¬ 
ter XIV. 

Turtles and Snakes. Line 
the bottom of a large box 
with Sheet-lead or zinc and 
place panes of glass in the 
sides for windows. Put 
earth, stones, and moss, 
and, if convenient, a few 
growing ferns in the box. This makes a good home 
for turtles and snakes. Snakes caught late in the 
fall will probably not eat anything through the winter, 
and they can be set at liberty in the spring. Turtles 
seldom eat in the winter, but will take flies, bits of 
meat, or pieces of cracker soaked in milk when 
hungry. ** The Vivarium ”, an illustrated book by G. 
C. Bateman, will be of great assistance to pupils who 
are willing to care for these animals. 

Frogs. In a box like that described in the preceding 
paragraph keep several frogs. In the winter frogs do 
not commonly take food. Live frogs can usually be 
bought in the markets. 

Slugs. These animals are easily kept if provided 
with moisture and food. They eat bread or cracker 
as well as many kinds of vegetables. 













8 


ANIMAL ACTIVITIES. 


Snails and Mussels. Collect pond-snails and put 
in a vessel of water with sticks, dead leaves, and 
growing plants. Place in the bottom of 
the dish two or three inches of sand and 
introduce one or two fresh-water mussels. 
Watch the movements of both snails and 
mussels. Find out how they breathe. 
The plants furnish food for the snails, and 
the mussels thrive without feeding, living 
for years in an aquarium like that just de¬ 
scribed. Watch for the eggs and growing 
young. Use directions in Chapter XV. 

Aquaria. The mussels just mentioned breathe the 
air dissolved in the water, and, on this account, fresh 
air must be supplied. There are several ways of doing 
this. The simplest method consists in furnishing 



Fig. 5.—A 
Water-snail 
( Planorbis ). 



Fig. 6. —Shell of a Fresh-water Mussel ( Anodon ). 


growing plants enough in the aquarium to take up 
the carbon dioxide gas exhaled by the animals, and at 
the same time to give the water a supply of oxygen. 
Such plants may be easily collected while looking for 
snails. Water-plants are also for sale at bird stores. 


MATERIAL FOR STUDY . 


9 


Another method of purifying the air in water consists 
in forcing a stream of air 
through it. This is not prac¬ 
ticable in most schoolrooms. 

Pouring fresh water against 
the side of the aquarium in 
such a way that many bub¬ 
bles of air are caught in 
the descending stream is a 
common and easy method. 

Large aquaria frequently have 
a constant supply of running 
water with a regular outflow. 

Such aquaria are hardly neces¬ 
sary in most schools. Small 
rectangular glass vessels and 
common battery-jars answer 

every purpose. Of course water 
lost by evaporation must be re¬ 
placed. With the aquatic animals 
mentioned here it is a good plan 
to depend partly on plants to 
change the air in the water, but 
in addition to this it is better to 
remove the greater part of the 
water from time to time and to 
replace it by a fresh supply. An 
easy way to accomplish this is to 
have all the aquaria placed on a 
shelf a little higher than the faucet 
from which water is to be supplied. 

A hose can be attached to the faucet 
for the purpose of filling the aquaria. 

In order to empty the vessels, it 
is only necessary to unscrew the 
hose from the faucet while it is still Fig - Duck- 

filled with water, being careful to 
keep the end of the hose in the aquarium under water. 




Fig. 8.—The Horn- 
wort. 



Fig. 7.— An American Pond- 
weed. 



10 


ANIMAL ACTIVITIES. 


In this way the water siphons over into the sink. To 
prevent the passage of insects through the siphon, attach 

it to a tunnel 
having the open¬ 
ing covered with 
wire gauze. 

Hydra. Collect 
small sticks and 
dead leaves, with 
some mud and 
water, from a fresh¬ 
water pond, or from 
ditches used for 
draining swampy 
Fig. io.— Other Pondweeds. places Place 

these in glass with 
growing fresh-water plants, and renew from time to 





Fig. ii.—T he Hydra ( magnified ). 

time the water lost by evaporation. Collect from 
several localities in separate jars, and label the jars 




MATERIAL FOR STUDY. 


n 


for convenience. Watch carefully for the appearance 
of either brown or green hydras. 

They may be seen without a magnifying-glass. If 
only eggs are present, they may not hatch for months, 



Fig. 12.—Water-fleas and Cyclops ( magnified). 


but sometimes adult hydras are captured attached to 
duckweed or other objects. Have several jars, and 
watch them all. Look for the appearance of buds on 
the sides of the hydras. Minute Crustacea (water-fleas 
and Cyclops) may appear in some of the jars. These 
are good food for hydras, and themselves furnish pleas¬ 
ing objects for study, both with and without the micro¬ 
scope. If either Crustacea or hydras appear, notice 
whether they prefer the light or the dark side of the 
jar. Add water only to replace that lost by evapora¬ 
tion. 

Some Water-breathing Insects. While collecting 
the hydras, look for objects that appear like moving 
sticks, or small moving rolls made of bits of leaves or 
pieces of sand. These are the larvae of caddis-flies. 
Watch them feed, and add material to the tubes which 
protect their delicate bodies. Keep plenty of plants 
about them. Larvae of other insects may be collected 


12 


ANIMAL ACTIVITIES . 


at the same time and kept in aquaria. If possible 
collect a water-boatman. Fig. 72 shows this insect 



Fig. 13.— Caddis-fly Cases. 


as it appears while swimming and while flying. A 
powerful aquatic insect is the large water-beetle (Dity- 
cus Marginalis). Fig. 15 shows the young and Fig. 



Fig. 15.— Larva of Dyticus. Fig. 16.—Larvaof Fig. 17.—Larva 

Whirligig Beetle. of a May-fly. 


73 shows the adult forms. The whirligig beetles seen 
in large numbers on the surface of fresh water have 
eyes adapted for seeing enemies in the air above and 




MATERIAL FOR STUDY. 


13 


in the water below at the same time. A young 
whirligig is shown in Fig. 16. Watch mode of 
breathing and of carrying air about. Observe also 
the manner of “feathering” the oars. Feed the 
beetle and larvae on bits of meat or small in¬ 
sects. 

Leeches. “ Blood-suckers ”, as the boys call them, 
are harmless and interesting tenants of an aquarium. 
Watch some of these animals, noting especially the 
mode of movement by means of contracting longi¬ 
tudinal and circular muscles. They feed only occa¬ 
sionally, and can be set at liberty before they suffer 
for food. At liberty they suck the blood from living 
animals. 

Crayfish. These may be bought alive in the mar- 


ab tho cep r 



Fig. 18.— Side View of Crayfish, an, antenna; r , rostrum; cep, cephalic 
portion; tho, thoracic portion of cephalothorax; ab, abdomen. 


kets. They may be kept in shallow water in aquaria 
and fed on bits of fish or meat. 

Tadpoles. These may be caught in ponds and 
brooks even late in the fall. Collect several sizes and 
keep them in a jar or jars. They feed on vegetable 
matter, eating chiefly the small green plants (confervae) 
which grow so rapidly in stagnant water exposed to 
sunlight. Select a particular individual and sketch his 



14 


ANIMAL ACTIVITIES. 


actual size from time to time, dating the sketches. 
Make these sketches as accurate as possible. When 
not convenient to catch tadpoles it is easy to buy 
them. 

Fishes. Obtain alive, by using a net, either horned 
pout (catfish) or bream. Goldfish can be bought in 
case of failure to get others. Feed with fish-food, a 
preparation of gelatin sold by dealers in goldfish. Use 
plants in the aquarium, and change the water about 
three times a week. Use a rectangular aquarium. 
Shield from the direct rays of the sun. 

Hydroids and Jelly-fish. Unless a school is situated 
where it is easy to obtain an abundant supply of salt 
water, not many marine animals can be well kept. 
Before undertaking seashore work, a copy of ‘ ‘ Seaside 




Fig. 19.—A Campanularian Hydroid Colony (Eucope diaphana). a, 
whole colony, one half natural size; b , single zooid magnified; 
c and d , stages of jelly-fish, magnified. 


Studies ’ ’ (Agassiz) should be accessible to both teacher 
and pupils. There are many small marine animals 
resembling the hydra. Among the most abundant of 
these are the campanularian hydroids, colonies of hydra¬ 
like animals. The colonies are brown in color, and 
look like mosses or similar plants. They grow on 



MATERIAL FOR STUDY. 


*5 


sea-weeds, on logs and sticks, and are sometimes at¬ 
tached to the shells of mussels. Find them at low 
tide and transfer them to a marine aquarium, made by 
filling a jar with salt water and introducing some marine 
plants collected on the rocks where 
the campanularians are found. Some 
closely related colonies are called 
sertularians. Hydractinia is the 
name given to a colony consisting 
of pink, salt-water hydroids found 
growing on the snail-shells occu¬ 
pied by hermit-crabs. 

Sea-anemones. These animals 
are hardy and may be transported 
for some distance in jars or pails of 
salt water. To obtain them, look 
in pools left by the tide in rocky 
places, or on rocky bottoms below Fig : 2 °VT A Ser ^! a ‘ 
low tide. I hey are sometimes found Agassiz, 
attached to the piles of wharves or 
bridges. They can be removed from the rocks by 
quickly slipping a broad, thin knife between the 
anemone and the rock. Their resemblance to hydras 

and to coral animals 
should be especially 
noted. Except as 
living specimens they 
are not of much value 
to beginners, as the 
prepared specimens 
are commonly too 
Fig. 21.—A Net for Collecting at the much distorted to 
Seaside. , , , ,, 

show structure well. 

Starfishes and Sea-urchins, These animals may 
be found in the same localities as the anemones. They 
are quite hardy and will live in salt-water aquaria. As 
they can be collected at any time during the year, it is 
as well to get the living specimens when ready to study 







i6 


ANIMAL ACTIVITIES. 


Chapter XIII. Keep one animal in each battery-jar 
with sea-water and a few marine plants. 

Sea-cucumbers. These animals are often found on 
beaches after a storm. They may be found on rocky 
bottoms in a depth of from three to six feet of water at 



Fig. 22.—Sea-anemones. 


low tide. It is easy to take them with a dip-net when 
once found. They are hardy and live well in aquaria. 
Compare with starfish and sea-urchin. 

Shrimps and Sand-fleas. Shrimps may be used in¬ 
stead of crayfish in studying Chapter X. They may be 
caught with a dip-net in shallow water at low tide. They 
can be kept in aquaria. Sand-fleas, sometimes called 










MATERIAL FOR STUDY . 


17 




Fig. 24.—A Sea-urchin. Part of the spines have been removed. 


sand-hoppers, are easily collected by overturning rocks 
left by the tide. 

Compare with 
shrimps. Collect 
also hermit-crabs. 

Marine Fish. 

Where there are 
conveniences for 
salt-water animals, 
a few small marine 
fish may be kept. 

No special direc¬ 
tions are necessary. 

Compare with 
other specimens of 

fish and use with 
Chapter XVI Fig. 23.—A Starfish. After Agassiz. 


THE PREPARATION AND CARE OF SPECIMENS. 


Prepared Specimens. In addition to living animals 
it is always necessary to have at hand a plentiful supply 


i8 


ANIMAL ACTIVITIES. 


of prepared specimens so preserved as to be examined 
to the best advantage. It should be a part of the work 
of the pupil to prepare at least a portion of this material. 

Killing the Specimens. Place some pieces of blot¬ 
ting-paper saturated with chloroform or ether in the 



Fig. 25.—A Sea-cucumber. Fig. 26.—A Hermit-crab. 


bottom of a jelly-tumbler provided with a tin cover 
(Fig. 28). In this grasshoppers, butterflies, and other 
small insects may be painlessly killed. It must be 
remembered that chloroform and ether are poisonous 



Fig. 27. —A Shrimp. 


substances, and that they must not be brought near a 
lighted lamp or fire, as they ignite very readily. 


MATERIAL FOR STUDY. 


19 


The cyanide bottle described in Part F of Bulletin 
No. 39, U. S. National Museum, can be used instead 
of the tumbler if desired. Animals larger than insects 
may be killed by chloroform or ether. Earthworms 
should be killed in dilute alcohol. Starfish and sea- 
urchins are often killed by placing 
them in hot, but not boiling, water. 

Preserving Specimens in Alcohol. 

Part M of Bulletin No. 39 already 
mentioned gives valuable directions 
for the preservation of specimens. 

Alcohol is the most important pre¬ 
serving fluid. For most specimens 
50 io alcohol should be used at first. 

This should be changed in a few 
days to a stronger solution, about 60%. If the speci¬ 
mens are to be permanently kept they should be 
transferred again to 70 % alcohol. Strong alcohol as 
bought of the dealers is about 95$ pure. This should 
be diluted some days before the specimens are put in 
it, to prevent the collecting of bubbles on the surface 
of the animals. Parts of animals for dissecting 
should be hardened gradually in alcohol. Hydras, 
hydroids, snails, mussels, and worms are best kept in 
alcohol. 

Preserving Specimens in Formalin. This liquid as 
usually bought is a solution of formaldehyde in water. 
For most purposes it should be diluted with water to 
make a 2% solution. Specimens to be used are kept 
in this fluid. 

Dried Specimens. For class use, butterflies may be 
kept in a tightly closed box containing naphthalin or 
camphor. Such specimens usually need to be preserved 
for a few months at most and can then be thrown away. 
Dragon-flies and other insects may be kept in the same 
box. Starfish may be dried by a slow heat after 
immersing for a time in hot water, not boiling, or after 
gradually hardening in alcohol. Sea-urchins may be 



Fig. 28. — Tumbler 
with Chloroform. 
Drawn by A. E. 
Sanford. 






20 


ANIMAL ACTIVITIES. 


preserved in the same way, but they make better speci¬ 
mens for study, if preserved in formalin or alcohol. 

Shells and Bones. To remove snails from their 
shells put them in hot water for a few moments. The 
shells may then be cleaned and dried. To clean fleshy 
matter from a skeleton like that of the starfish use a 
dilute solution of caustic potash. Sometimes it is well 
to boil specimens in that liquid. The bones of larger 
animals can be cleaned enough for class use by simply 
boiling and removing the fleshy parts. When such 
specimens are to be kept for a long time more care is 
needed, and books containing more specific directions 
should be consulted. Part C of Bulletin No. 39, pre¬ 
viously mentioned, is helpful. 


MATERIAL FOR WINTER AND SPRING. 

The preceding directions are for classes which begin 
Zoology in the fall. When the work begins in the 



in cold weather. They are 


spring the order of 
work should be modi¬ 
fied somewhat, begin¬ 
ning with Protozoa and 
reaching the subject of 
Arthropoda after warm 
weather brings the 
living specimens again 
within easy reach. 
Even in winter much 
material can be pro¬ 
cured by the pupils for 
their study. 

Cockroaches. Cock¬ 
roaches were originally 
southern insects. They 
are now distributed 
almost everywhere, and 
are fairly abundant even 
most easily collected at 





MATERIAL FOR STUDY. 


21 


night in warm places where there is a plentiful supply 
of household food. A sugar-refinery often furnishes 
an abundant supply of these insects. They may be 
kept alive as in the case of grasshoppers. With a few 
obvious changes in the directions and questions, the 
cockroach may be substituted for the grasshopper in 
studying Chapter III. 

Butterflies and Moths. Although adult forms of 
these insects are not abundant in cold weather, their 
eggs, cocoons, and chrysalids are easily obtained. In 
late winter or early spring pupils should collect speci¬ 
mens of the large mourning-cloak butterfly (Vanessa 



Fig. 30.— Mourning-cloak Butterfly (Vanessa antiopa). 


antiop a), which shows the wear due to its winter sleep, 
and is ready to produce eggs for the summer brood. 
The eggs may be reared, the larvae feeding on leaves 
of willow or birch. On apple- and cherry-trees may 
be found the eggs of the tent-caterpillar moth. These 
eggs are glued to the stem in a mass. The large 
grayish-brown cocoons of the Cecropia moth are often 
found on pear-trees or other fruit-trees. Eggs, cocoons, 
and chrysalids should be brought to the schoolroom 
and placed under such conditions that hatching and 
growth may be watched. 



22 


ANIMAL ACTIVITIES. 


Other Insects. Eggs of spiders are easily found in 
winter. They should be kept in tumblers and watched. 
Nests of paper-making wasps are interesting. They 
often contain sleeping queens waiting for a higher tem- 



Fig. 31.—A Wasp’s Nest. Fig. 32.— Cocoon of Cecropia. 

From a Photograph. 


perature in order to start other colonies. Insects in 
various stages of metamorphosis pass the winter hidden 
away from birds and other enemies. Locality and cir¬ 
cumstances must determine what sort of specimens 
pupils should search for. With the advent of spring 
one can obtain nearly, if not quite, all the specimens 
already mentioned as obtainable in the fall. 


MATERIAL FOR STUDY. 


2 3 


and jelly-fish 



For Aquaria. Hydroids, hydras, 
for the most part die off in win¬ 
ter, but sea-anemones, starfish, 
hermit-crabs, shrimps, and cray¬ 
fish can all be obtained through¬ 
out the year. Snails and mussels 
are also easily kept at all times, 
as are also tadpoles and frogs. 

In the spring the eggs of frogs and toads should be 
placed in aquaria and watched. 

Birds. Winter is the best time to begin the out¬ 
door study of birds. Familiarity with the birds which 
remain north throughout the winter prevents much of 


Fig. 33.— Eggs of Frog 
just Laid. 



Fig. 34. —Eggs of Frog a Few Hours after Laying. 


the confusion which so annoys the novice when he tries 
to observe the newcomers at the time of the spring 
migration. A study of crows, blue jays, and chicka¬ 
dees, during cold weather should form a part of the 
work for winter. English sparrows must not be 
despised as objects of study, and their habits, both in 
captivity and out of doors, should be watched. 



CHAPTER III. 


ACTIVITIES COMMON TO ALL ANIMALS. 

Matter. The books on physics tell us that matter 
is anything having extension, i.e., having length, 
breadth, and thickness. Living matter we call or¬ 
ganic, and matter which is not alive, and, as far as we 
can see, never has been alive, we call inorganic. 

Living Matter. Living matter dies. It always 
returns sooner or later to the inorganic world from 
which it derives the materials by means of which it 
keeps its living machinery active. 

Organisms grow, not by adding matter to the out¬ 
side, as do crystals when they increase in size, but by 
taking substances into the body, and there building 
them into matter like themselves. 

Before growth ceases, plants and animals reproduce. 
Some small portion of the body separates from the rest 
and begins an independent existence, repeating, very 
nearly, the life-history of its parents. In most cases the 
part which separates for the new life must join with a 
part of another individual before it can grow. Doubt¬ 
less pollen and ovule are familiar terms to all who will 
use this book. 

Living things, too, seem to be capable of movements 
which differ from the movements of inorganic things. 
A living tree moves with the wind just as inorganic 
things move, but it also has going on within it move¬ 
ments which differ entirely from any movements of 
which inorganic matter is capable. 


24 


ACTIVITIES COMMON TO ALL ANIMALS. 


2 5 


Plants and Animals. The differences between 
higher animals and plants are so obvious that we need 
never mistake one for the other; but, as we shall see, 
the differences grow less and less as we consider simpler 
and simpler organisms. Among the simplest living 
bodies the processes of life go on; but we do not know 
whether to call the living things themselves plants or 
animals. 

Definitions. The science which treats of living 
matter is Biology. The branch of Biology treating of 
plants is Botany, and the branch treating of animals is 
Zoology. 

The study of the form, structure, and position of the 
parts of a plant or an animal is Anatomy. Minute 
Anatomy studied with the microscope is Histology. 

The study of the functions or uses of all parts of an 
organism is Physiology. 

Activities of our own Bodies. We may learn what 
the most important activities of animals are by con¬ 
sidering the chief activities of our own bodies. While 
our ability to move readily from place to place, and to 
perform the many muscular acts of daily life, is doubt¬ 
less the most noticeable sort of activity which we share 
with other animals, it is not the most fundamental. 
Back of all movement there must be a source of power. 
In these days, men make machines which seem almost 
alive. In these some sort of power which we can 
understand causes all the movements. Springs and 
weights move clocks, steam-pressure turns the wheels 
of factories, and electric currents move our street cars. 

Our Bodies Chemical Engines. Sources of power 
can usually be traced back to heat. The movements 
of a steam-engine are due to energy set free by the 
burning of coal. The burning of coal is a chemical 
activity. The heat is caused by the union of two 
elements, carbon and oxygen. It has been found that 
the movements of living things are also due very 
largely to chemical action. Just as coal burns or 


26 


ANIMAL ACTIVITIES. 


oxidizes in a furnace and produces energy or power to 
work, so the various materials of which our bodies are 
made oxidize and set free the energy by which we 
perform the varied movements of our bodies. In a 
very true sense, then, our bodies may be called chemi¬ 
cal engines. 

Waste and Repair. The furnace which furnishes 
power for any kind of machinery must constantly 
receive new material and give out waste products. 
Without a constant supply of coal and air, the fire goes 
out and work stops. The chimney must be kept clean 
in order to allow the gases produced by the fire to pass 
out, and the ashes must be raked away as fast as they 
are formed, to make space for new fuel. In the same 
way every living animal takes into its body substances 
corresponding to the fuel of a furnace, and it as con¬ 
stantly gives out the waste products which would soon 
cause death if they should remain. In order that we 
may know these substances better, a few simple experi¬ 
ments may be considered. 

Experiment. Water. Using the apparatus shown 
in Fig. 35, pour water and a 
little sulphuric acid into the U 
tube, and place test-tubes filled 
with water over the ends of the 
wires. When the circuit is 
closed notice that bubbles of 
gas arise from the wires and 
collect in the upper part of the 
test-tubes. Note the fact that 
water is separated by a current 
of electricity into two invisible 
gases, and that, after a time, 
one tube contains twice as much 
gas as the other. The larger 
amount of gas is hydrogen, and 
Light the hydrogen, noting the 
Into the top of the 



Fig. 35. — Apparatus for 
Decomposing Water. 
Drawn by A. E. San¬ 
ford. 


the smaller, oxygen, 
fact that it burns very readily. 












ACTIVITIES COMMON TO ALL ANIMALS. 


27 


tube containing oxygen thrust a glowing coal (carbon) 
and see that it relights. Water is composed of two 
gases. Hydrogen burns easily in air, and oxygen aids 
the burning of hydrogen, of carbon, and of other sub¬ 
stances. 

Elements and Compounds. Because hydrogen and 
oxygen cannot be further separated into other sub¬ 
stances they are called elements . Water, because it 
is formed by the union of two elements, is called a 
compound. Carbon is also an element. 

Experiment. The Oxidation of Magnesium. Mag¬ 
nesium is an element. To a piece of wire made of this 
element apply a lighted match and notice the produc¬ 
tion of heat and light. Examine the white powder 
produced. The oxygen from the air has united with 
magnesium and formed magnesium oxide. This white 
powder, the magnesium oxide, weighs more than the 
magnesium used. The process is oxidatio?i. 

The oxidation of hydrogen produces hydrogen oxide, 
or water. The oxidation of carbon produces carbon 
oxide, commonly called carbon dioxide. Magnesium 
oxide is a solid, hydrogen oxide is a liquid, and carbon 
dioxide is a gas. In all cases heat and energy are 
produced by oxidation. 

Experiment. The Oxidation of Phosphorus. Phos¬ 
phorus is an element obtained from the bones of ani¬ 
mals. Caution must be used in experiments with 
phosphorus as it ignites so readily. Remove a piece 
of phosphorus from the water and allow it to dry on a 
piece of blotting-paper. Note the smoke arising. This 
is phosphorus oxide. Touch the phosphorus with a 
warm wire. Note the increased rapidity of the oxida¬ 
tion. The same amount of heat is produced by the 
oxidation of phosphorus whether the oxidation is slow 
or rapid. Phosphorus oxide is formed in both cases. 

Experiment. Nitrogen in the Air. Air is almost 
wholly a mixture of nitrogen and oxygen. Cover the 
top of a large cork with asbestos and put on it a small 


28 


ANIMAL ACTIVITIES . 


piece of phosphorus. Float the cork on water in a 
soup-plate and light the phosphorus, at the same time 
lowering over it a jar of air, in such a manner that the 
mouth of the jar just dips below the 
surface of the water in the plate (Fig. 
36). The phosphorus oxide formed 
dissolves quickly in the water. The 
water rises in the jar to replace the 
oxygen used up, showing that about 
one fifth of air is oxygen. 

Remove the jar from the plate 
and thrust into the gas a lighted 
match. This colorless gas forming 
about four fifths of the air is nitro¬ 
gen. It will not burn or aid the 
burning of other substances. This 
element is found in all animal bodies 
united with other elements to form 
compounds. Bread and meat contain compounds 
partly composed of nitrogen. 

Experiment. The Element Carbon in Starch and 
Sugar. Heat in the bottom of a test- 
tube a small amount of sugar (Fig. 

37). Notice the water which col¬ 
lects on the sides of the tube. What 
are two elements found in sugar ? 

Heat slowly until no more steam 
escapes, break the tube and examine 
the residue. It is charcoal, a form 
of carbon. What three elements in 
sugar ? 






Fig. 36.—Apparatus 
for Removing 
Oxygen from Air. 
Drawn by A. E. 
Sanford. 


Repeat this experiment,using starch 
and wood. 

Graphite and diamond are other 
forms of carbon. 

Experiment. Carbon Dioxide. Burn 


Fig. 37.— Heating 
a Test-tube. 
Drawn by A. E. 
Sanford. 


in a covered 


bottle a little charcoal attached to a wire. When it 
ceases to glow remove it, and shake up the gas in the 














ACTIVITIES COMMON TO ALL ANIMALS. 


29 


bottle with lime-water. The milky appearance of the 
water proves that the gas, carbon dioxide, is present 
in the bottle. How did the gas get in the bottle ? 

Experiment. Carbon Dioxide in the Breath. Breathe 
through a glass tube into a test-tube containing a little 
lime-water. What does the milky appearance of the 
lime-water prove ? Whence came the carbon dioxide ? 
How was it produced ? 

Experiment. The Oxidation of Hydrogen in our 
Bodies. What collects when we breathe on a cold 
glass ? Whence comes the water ? The hydrogen 
enters the body with the food. How does the oxygen 
enter the body ? 

Substances Taken into the Body and Substances 
Excreted. It has been found that the greater part of 
the substances taken into the body are compounds of 
hydrogen, oxygen, nitrogen, and carbon. These 
enter the body as food. Oxygen also enters the 
body in breathing. It has been found that the sub¬ 
stances regularly excreted from the body by the lungs, 
by the skin, and by the kidneys are carbon dioxide, 
water or hydrogen oxide, and a compound containing 
nitrogen and hydrogen, called urea. In this way the 
four elements which enter the body as complex com¬ 
pounds are all finally excreted as very simple com¬ 
pounds. 

A Summary of Activities. All animals take food 
of some kind. As in our bodies, so in the bodies of 
all other animals, the food must be chemically changed 
to build up tissues and furnish material for oxidation. 
Although all other animals do not have lungs, skin, 
and kidneys like ours, they nevertheless must excrete 
the materials which result from the oxidations and 
other chemical changes in the body. All animals also 
reproduce. All are capable of movements different 
from the movements of inorganic things. All, too, are 
able in some way to establish communication with the 
outside world. For this purpose we are endowed with 


30 


ANIMAL ACTIVITIES. 


special organs for seeing, hearing, smelling, tasting, 
and feeling. By these organs we discover the world 
about us. Many animals have not these organs of 
sense. Many, indeed, have no organs of any kind, 
yet all animals seem to possess, to some extent, the 
ability to discover their surroundings. If no other 
sense be present, something like our sense of feeling 
seems to be always active. 

We may summarize the most important activities of 
animals as follows: 

(a) Taking food and oxygen. 

( b) Nutrition. 

(c) Excretion. 

( d) Reproduction. 

(e) Movement. 

(f) Discovery. 

Respiration combines in most animals the two im¬ 
portant functions of taking oxygen and excreting waste 
matter. 

Physiology and Anatomy. In studying animals 
we wish most of all to know their activities. But in 
order to understand these activities one must know 
certain facts about the structure of the animals to be 
studied. A sewing-machine has only one activity or 
function, but one must know the form and position of 
many parts before one knows just how the sewing is 
done. When we speak of the six activities mentioned 
we are dealing with Physiology. When we study the 
parts of an organism to learn their positions and shapes 
we are dealing with Anatomy. Evidently, then, anat¬ 
omy and physiology must be studied together in the 
science of Zoology. We do not study anatomy in 
order to become familiar with many new names, but in 
order to understand the activities or uses of the parts. 


ACTIVITIES COMMON TO ALL ANIMALS . 


3 1 


VOCABULARY. 


A nat'o my (Gr. ana, up, and 
temno, cut), the science which 
treats of the structure of organ¬ 
isms. 

Bi ol'o gy (Gr. bios , life, and logos, 
a discourse), the science of living 
things. 

Bot'a ny (Gr. botania, a plant), 
that part of Biology which treats 
of plants. 

Car'bon (Lat. carbo, coal), an ele¬ 
ment found in all organic com¬ 
pounds; charcoal, graphite, and 
diamonds are forms of this ele¬ 
ment 

Car'bon di ox'ide, a heavy, color¬ 
less gas, formed by the breathing 
of animals and by the burning 
of substances containing car¬ 
bon. 

Ex cre'tion (Lat. ex, out, and cer- 
no, separate), the act of throw¬ 
ing off waste matters from the 
body. 

Func'tion (Lat. fungor, execute), 
the action of any part or organ of 
a plant or animal. 

His tol'o gy (Gr. hist os, a web, or 
tissue, and logos'), the study of 
minute anatomy. 

Hy'dro gen (Gr. hydor, water, and 
gignomai , be born), a colorless, 


gaseous element forming a part 
of water. 

In or gan'ic, not organic. 

Mag ne'si um (Gr. Magnesios , a 
district in Thessaly), a silver- 
white, solid, metallic element. 

Mat'ter (Lat. materia, stuff), any¬ 
thing having extension. 

Ni'tro gen (Gr. nitron, nitre, and 
gignomai), a colorless, gaseous 
element composing four fifths of 
the air. 

Nu tri'tion (Lat. nutrio, feed), a 
series of processes by which liv¬ 
ing things maintain their life and 
growth by appropriating food. 

Or gan'ic (Gr. organon, an organ), 
pertaining to plants and animals. 

Ox i da'tion, the process of uniting 
chemically with oxygen. 

Or'gan ism, a living plant or ani¬ 
mal. 

Ox'y gen (Gr. oxys, sharp, and 
gignomai), a colorless, gaseous 
element, forming one fifth of the 
air. 

Phys i ol'o gy (Gr. physis, nature, 
and logos), the science which 
treats of living things. 

Zo ol'o gy (Gr. zoon , an animal, 
and logos), that part of biology 
which treats of animals. 



CHAPTER IV. 


GRASSHOPPERS AND CRICKETS. 

Directions for Work. Collect full-grown and partly 
grown locusts or grasshoppers. Place some of the 
living insects in tumblers with fresh lettuce-leaves. 
Allow ventilation. Why ? Watch the insects care¬ 
fully and compare with a prepared specimen. In your 
note-book answer the questions below. 

Shape of Body, What is the shape of the body ? 
Are the two sides alike (bilateral symmetry) ? 

Is the skeleton or hard part of the body external or 
internal ? 

The Abdomen. The chief divisions of the body are 
the head, thorax, and abdomen. How many segments 
has the abdomen ? 

Count the segments of the abdomen in several 
specimens. Is the number the same in all cases ? 

Do you find a row of breathing-holes (spiracles) 
along either side of the abdomen ? 

Do you find a ridge running lengthwise along the 
abdomen just below the spiracles ? This ridge repre¬ 
sents the softer parts of the segments. These softer 
portions enable the insect to move the upper and lower 
parts of the segments farther apart to take in air while 
inhaling. When they are brought together again the 
air is expelled. The upper hard part of each segment 
is called the tergum, the under part is the sternum, 
and the more flexible part on either side the pleurum. 
Can you see the movement of the abdomen made by 
breathing ? 


32 


GRASSHOPPERS AND CRICKETS . 33 

Do you find the so-called ear-drum (tympanum) on 
the first segment of the abdomen ? 

The female grasshopper has organs at the end of the 
abdomen for placing her eggs in the ground (oviposi¬ 
tors). 

Do you find both male and female grasshoppers ? 
Sketch a side view of a grasshopper’s abdomen X 5- 

The Thorax. What appendages are attached to the 
thorax ? How many segments in the thorax ? 

How many legs do you find ? Are they jointed ? 
How do they differ in size ? Sketch one of the hind 
legs, indicating all the parts X 5 - 

How many wings do you see ? Are any of the 
wings folded ? How ? Sketch a front and a hind 
wing fully extended X 5 - 

To what segments are the wings attached ? 

What can you say of the grasshopper’s powers of 
locomotion ? How many times its length can a grass¬ 
hopper jump ? Do the grasshoppers you have seen use 
their wings when they jump ? How do the wings of 
young grasshoppers compare with those of full-grown 
insects ? 

The Head. How many feelers do you find on the 
front of the head (antennae) ? Are they segmented ? 
What is their shape ? How does their length compare 
with the length of the body ? Sketch a side view of 
the head showing feelers. 

How many eyes do you find ? Compound eyes are 
made up of parts called facets. Small, simple eyes are 
called ocelli. How many compound eyes has the 
grasshopper ? How many ocelli ? Where are the 
eyes and ocelli situated ? Sketch a part of a com¬ 
pound eye as seen under a microscope. 

What is the shape of the upper lip (labrum) ? 
Sketch. 

Under this lip do you find hard jaws (mandibles) ? 
How many ? What color ? What shape ? In what 
direction do they move ? Sketch. 


34 


ANIMAL ACTIVITIES. 


Do you find a tongue ? 

Do you find a pair of softer jaws (maxillae) behind 
the mandibles ? Sketch. 

What is the shape of the lower lip (labium) ? 

Do any of the mouth-parts have feelers (palpi) ? 
Where situated ? How many ? 

Does the insect bite or suck its food ? Notice the 
movements of its mouth-parts. 

Touch gently the grasshopper’s feelers with a tooth¬ 
pick or stick. Touch in the same way other parts of 
the body. Where is it most sensitive to touch ? 

How far can a grasshopper see ? How do you 
determine this ? Can the grasshopper hear ? Give a 
reason for your answer. Does the grasshopper have 
the sense of smell ? 

What can you now say about the grasshopper’s 
mode of taking food ? its respiration ? locomotion ? its 
organs of sense or discovery ? 

Summary of Drawings* (a) Side view of abdomen 
X 5 - 

(< b ) Sketch of one of the second and one of the third 
pair of legs X 5 • 

The parts of the leg, beginning at their union with 
the body, are coxa, trochanter, femur, tibia, and tarsus. 
Indicate these parts in your drawing. 

(c) Sketch of front and hind wings X 5- 

( d ) Side view of a grasshopper’s head X 5- 

( e ) Sketch of mandible X io. 

(/) Sketch of maxilla X io. 

(g) Sketch of upper lip X 20. 

(A) Section of compound eye (microscope). 

Internal Structure, If we wish to examine the 
internal structure of a grasshopper, we may prepare 
specimens by hardening them in alcohol. This changes 
the color and to some extent alters the size and general 
appearance of the organs. On this account it is well 
to examine a freshly killed specimen along with the 
alcoholic specimen for purposes of comparison, 


GRASSHOPPERS AND CRICKETS . 35 

For the purpose of dissection a female grasshopper 
should be pinned to the bottom of a dissecting-pan and 
covered with water. The dorsal wall of the abdomen 
should then be cut away with a pair of scissors, care 
being taken to notice the delicate tube, the heart, lying 
along the back. In the freshly killed specimens, the 



Fig. 38. —The Parts of a Locust, a, head; b , eye; c, antenna; d,f, i, 
thorax; ab, abdomen. 


tracheae, or air-tubes, connecting with the spiracles on 
the outside, and ramifying to all parts of the body, 
may be easily seen. At the same time a cluster of 
long, oval, yellow eggs may be seerf on each side of 
the body, near the anterior part of the abdomen. From 
these a tube, the oviduct, leads backward to the ovi¬ 
positors. Below the heart the digestive canal may be 








36 


ANIMAL ACTIVITIES. 


seen, consisting of the oesophagus, or gullet, a large 
crop, a stomach with many tubes called gastric caeca, 
and an intestine reaching to the anal opening. Lying 
along the ventral portion of the abdomen are masses 
of nerve-matter called ganglia, a double mass or pair 
of ganglia to each segment. These are connected by 
nerves. All the ganglia, with one exception, the 
supraoesophageal ganglion, or brain, lie below the 
digestive tract. 

This arrangement of organs, the heart dorsal, the 
nervous system ventral, and the digestive tube between 
is characteristic of insects. It is interesting to observe 



Fig. 39.—Comparison of Grasshopper and Man. A, anterior; P ; pos¬ 
terior; D , dorsal; V,\ ventral; n, nervous system; h., heart; /, food- 
tube. 


how this arrangement compares with that in the human 
body (Fig. 39). ♦ 

Taking Food. The grasshopper lives entirely on 
vegetable food. Although its mouth-parts appear 
much complicated, they are well adapted for their 






GRASSHOPPERS AND CRICKETS . 


37 


work. The palpi feel about and locate the juicy parts 
of plants, the maxillae seize and hold them in position, 
while the hard mandibles tear the food into bits and 
pass it along to the digestive organs. 

Plants are able to build from mineral substances the 
materials which are useful food for the grasshopper, 
thus illustrating the well-known fact that without plants 
animals would die. Even animals which never eat 
plants subsist on other animals which depend on 
plant-food. As far as we know animals are unable to 
take nitrogen unless it has been previously made into 
plant-tissues which are suitable for animal food. 

Nutrition. It is not our purpose here to describe 
in detail the processes of nutrition in animals having 
so highly developed a digestive system as we find in 
the grasshopper. It is enough to say that the food 
passes through a long tube extending from the mouth 
to the anal opening at the posterior part of the body. 
This tube is often called the food-tube or alimentary 
canal. In the grasshopper and similar insects it 
is enlarged in one place to form a gizzard or grind¬ 
ing stomach. In some grasshoppers this gizzard is 
armed with teeth. There are also two other enlarge¬ 
ments known as the crop and the stomach. In its 
course through this tube the food is acted upon by 
fluids which soften it and change it chemically so that 
the nutritive portion is able to soak through the walls 
of the food-tube into the blood, which distributes it to 
all parts of the body, where it is used to build up tissue 
or to serve as fuel for heating the body. The portion 
of the food which is not so softened passes through the 
tube and is finally expelled from the body at the anal 
opening. 

Respiration. Taking Oxygen and Excreting Waste 
Substances, Food is useless to animals without a 
supply of air and an outlet for carbon dioxide, water, 
and urea. Man regularly inhales and expels air about 
eighteen times a minute. This process is so important 


38 


ANIMAL ACTIVITIES. 


that we often speak of the “ Breath of Life ”. If we 
cover the holes along the sides of the grasshopper s 
body, so that no air can enter, he dies, just as we 
should die if deprived of air. Throughout animal life 
this same necessity for air exists. 

The air used by the grasshopper for breathing pur¬ 
poses enters the body through little holes along the 

sides of its abdo¬ 
men and thorax. 
Eight of these 
openings may be 
easily seen on 
Fig. 40.— The Trachea of an Insect ( magni - each side of the 
fi ed Y abdomen, and 

two others o n 

each side of the thorax. These holes, or spiracles, 
open into air-tubes, called tracheae, which divide and 
subdivide in order to send branches to every part of 
the body, even into the wings. These tubes and their 
branches are surrounded by blood-vessels through 
which blood is constantly coursing. The oxygen of 
the air filters through the walls of the tracheae into 
the blood, and the carbon dioxide, water, and other 
waste substances in the blood pass through the same 
walls in the opposite direction. Such an interchange 
of gases through a membrane is called osmosis. Not 
only do these breathing-tubes carry oxygen to the 
blood and remove the waste products of respiration, 
but they also render the body very light, enabling the 
insect to rise easily in the air. In addition to excreting 
waste substances by breathing, the grasshopper pours 
urea into the food-tube and thence out of the body. 

Reproduction. But animals or plants never eat 
enough to make them grow or live forever. In many 
common plants a single cell, called an ovum, is set 
apart and fertilized by union with another cell to form 
a seed, which, under proper conditions, reproduces the 
plant. In the grasshopper the egg corresponds to the 




GRASSHOPPERS AND CRICKETS. 


39 


seed of the plant. It, too, is a single fertilized cell set 
apart for reproduction. The grasshopper deposits her 
eggs in the ground, using for this purpose the oviposi¬ 
tors at the end of her abdomen. From these eggs 
there hatch tiny insects much like their parents in 
shape, but destitute of wings. After a few days of 
eating, the little grasshopper becomes too large for his 
hard skin (exoskeleton), and proceeds to change it. 
The process of crawling out of the old skin is called 




Fig. 41. —Cockroach and Cast Skin. 

moulting. In this way he moults five times, after each 
moult appearing in every way more like the parent 
grasshopper. Tike most other insects grasshoppers 
deposit an enormous number of eggs. 

Discovery. If one touches a stone it does not move, 
but if, on the other hand, one touches the feelers of a 
grasshopper, or moves a stick in front of its eyes, there 
is a movement in response to the irritation. This 
movement is usually entirely involuntary, like the 













40 


ANIMAL ACTIVITIES. 


movement of the eyelids when a sudden blow is 
threatened. Very simple and familiar illustrations of 
this power are common even among plants. In higher 
animals the response to external stimuli is often so 
complicated with voluntary movements that the two 
can hardly be distinguished, but in every animal there 
doubtless exists the power to respond in some way to 
movements of the world outside its own body. These 
movements may affect the animal through simple 
touch, or through any or all of the other senses. 
Every animal has at least one of the five senses. 



Sight. Although the eyes of the grasshopper are 
large and composed of many parts, his power of vision 
is doubtless far inferior to ours. Many experiments 
have been made on the sight of insects, and all seem 
to show that they can neither see far nor clearly. The 
compound eyes of insects, as we have seen, are made 
up of many hexagonal facets. Each of these facets 
has a tiny lens for focussing the rays of light on a 
nerve which transmits vibrations caused by these rays 
to the nerve-centres within. 

Hearing. The hearing of the grasshopper is prob¬ 
ably more acute than his sense of sight. Vibrations 
of the air set in motion the ear-drum on the first seg¬ 
ment of the abdomen, and these are conveyed to 
nerves which connect with nerve-centres in the thorax. 
The fact that grasshoppers and their relatives are able 
to make noises which doubtless are understood by 
their friends is a reason for believing that they can 
hear. These noises do not issue from organs of speech 






GRASSHOPPERS AND CRICKETS. 


4i 



Fig. 43.—Portion of the Cornea 
of a Fly’s Compound Eye 
( magnified ). 


like ours, but are more like the sounds we produce 
when playing on a violin. Careful observation of a 
male cricket will best show 
us a method of stridulating , 
as this process of insect-talk¬ 
ing is called. Watching a 
cricket as he stridulates, 
one can see that the outer 
wings are raised and rapid¬ 
ly moved from side to side. 

If, now, the wing be ex¬ 
amined with a microscope, 
a clear membrane remind¬ 
ing us of a drum-head will 
be seen on each wing, and 
on the under side of each 
outer wing will be found an enlarged roughened cross¬ 
vein which is used like the bow of a violin, being drawn 
across the edge of the opposite wing- 
cover to set in motion the membranous 
drum-heads. 

The cricket’s organ of hearing is situ¬ 
ated on the tibia of the front leg. Some 
insects hear by means of hairs on the 
antennae or elsewhere which move in 
unison with vibrations about them. In 
some cases insects may be able to hear 
sounds entirely inaudible to human ears. 

Taste and Smell. The sense of taste 
probably resides in the palpi. That the 
grasshopper can smell is evident from 
the way in which he chooses his food, 
and also from the fact that certain odors 
seem disagreeable to him. 

Touch. That the grasshopper pos¬ 
sesses the sense of touch is easy to prove, and that 
the antennae are especially sensitive as tactile organs 
is equally evident. The antennae are provided with 



Fig. 44.—The 
Hearing 
Organ of a 
C r i c k e t 
( magnified ). 



42 


ANIMAL ACTIVITIES. 


hairs which seem to increase their sensibility, and they 
are connected with the nerve-centres within the body, 
as are the other organs of sense. 

Movements. In addition to the motion called forth 
by irritation of the sense-organs,, the grasshopper is 
evidently able to move on his own account. He can 
walk, fly, or jump where and when he wishes. The 



Fig. 45.—The Stridulating Organ of a Cricket. a , large vein; b , 
roughened cross-vein; c, membrane. 

adaptation of the legs to the mode of life needs no 
comment. The structure of the wings, however, may 
be briefly considered. The wings are outgrowths of 
the hard exoskeleton. They are composed of a frame¬ 
work of double tubes over which is stretched a mem¬ 
brane. The inner tube of one of the veins carries air. 
The outer tube surrounding this is filled with blood. 
Thus the wing becomes an organ of respiration as well 
as an organ of flight. Lightness and strength are also 
obtained at the same time. 

Comparison of Grasshopper and Cricket. Crickets 
are easily collected. They may be studied in the same 
way as the grasshopper. In writing notes concerning 
the cricket, make use of the new descriptive words 
learned while, studying the grasshopper. Write in your 
note-book only such facts as can be made out from the 
specimens. At the top of the page in your note-book 
write “Grasshopper and Cricket”. Draw a vertical 







GRASSHOPPERS AND CRICKETS. 


43 


line down the middle of the page. At the top of one 
column write “ Resemblances ”, and at the top of the 
other column write “Differences”. In these spaces 
write all the resemblances and differences you can 
make out from actual observation. 

Notice with especial care the tibia of the front leg in 
order to see the ear-drum. 

Look on the under side of the wing-cover of the 
male cricket for the roughened vein used in stridulating. 

The pair of appendages at the end of the abdomen 
are called stylets. 

Make a drawing of a cricket as you see it. 

Questions. I. How do a grasshopper’s activities 
differ from those of man ? 

2 . Is it an advantage in insect-life to have the 
nervous system on the ventral part of the body ? 
Why? 

3. In what respects is a segmented body an advan¬ 
tage to an animal ? 

4. At what time of year are grasshoppers most 
abundant ? 

5. Whence come the grasshoppers seen in the fields 
in spring ? 

6. Would it be wise to rid the world of grass¬ 
hoppers ? Why ? 

7. Why does the grasshopper breathe ? What 
chemical changes occur in breathing ? 

8. What is the color of the grasshopper’s blood ? 

9. What senses has the grasshopper ? 

10. What are the differences between organic and 
inorganic things ? 

11. What are the points of similarity ? 

12. What are some of the differences between plants 
and animals ? 

Topics for Reports. The Locust Scourge. Locusts 
as Food. Howto Destroy Locusts. The Life-history 
of a Locust. The Cockroach. Crickets. Walking- 
sticks. 


44 


ANIMAL ACTIVITIES . 


VOCABULARY. 


Ab do'men (derivation uncertain), 
the posterior part of the body in 
insects. 

An ten'na, pi. antenna: (Gr. ana , 
up, and teino, stretch), a feeler 
growing from the head of an in¬ 
sect. 

An te'ri or (Lat. ante, before), 
front. 

Bi lat'er al (Lat. bis , twice, and 
latus, side), having two sides 
alike. 

Chi'tin (Gr. chiton , a tunic), the 
horny substance forming the exo¬ 
skeleton of insects. 

Cox a (Lat. coxa , the hip), the joint 
of an insect’s leg next the body. 

Dor'sal (Lat. dorsum , the back), 
opposed to ventral. 

Fac'et (a diminutive of face), a part 
of a compound eye. 

Fe'mur (Lat. femur , the thigh), 
the thigh. 

La'bi um (Lat. labium , lip), the 
lower lip of an insect. 

La'brum (Lat. labrum , lip), the 
upper lip of an insect. 

Man'di ble (Lat. mando , chew), 
the hard, biting jaw of an insect. 

Max il'la (Lat. macero , soften), 
the softer jaw behind the man¬ 
dibles of an insect. 

Mes o tho'rax (Gr. mesos, middle, 
and thorax'), the middle segment 
of the thorax. 

Mela mor'pho sis (Gr. met a, over 
or beyond, and morpho , form), 
the changes which take place in 
an animal from egg to adult. 

Met a tho'rax, the posterior seg¬ 
ment of the thorax. 

Moult (Lat. muto , change), the 
shedding or casting of the exo¬ 
skeleton. 

Nymph (Gr. nymphe, a bride), a 
name applied to the young of 
sorae insects, as the grasshopper. 


0 cel'lus (Lat. dim. oioculus, eye), . 
a small eye. 

0 vi pos'i tor (Lat. ovum , egg, and 
pono , place), an instrument for 
depositing eggs. 

Pal'pus, pi. palpi (Lat. palpo, feel), 
a feeler growing from one of the 
mouth-parts. 

Pleu'rum (Gr. pleuron , rib), the 
side of the segment of an insect. 
See Fig. 

Pos te'ri or (Lat. post , after), hind¬ 
er. 

Pro tho'rax (Gr. pro, before, and 
thorax ), the first segment of the 
thorax. 

Spir'a cle (Lat. spiraculum, air¬ 
hole), a breathing-hole. 

Ster'num (Gr. sternon, breast), the 
ventral portion of the segment of 
an insect. 

Strid u la'tion(Lat. strido, creak), 
a creaking noise made by in¬ 
sects. 

Tar'sus (Gr. tarsos, a flat surface), 
the foot of an insect. 

Ter'gum (Lat. tergum, back), the 
dorsal part of the segment of an 
insect. 

Tho'rax (Gr. thorax, the chest), 
the middle division of an insect’s 
body. 

Tib'i a (Lat. tibia, shin-bone), the 
part of an insect’s leg between 
the femur and foot. 

Tra'che a (Gr. tracheia , rough), 
one of the breathing-tubes of an 
insect. 

Tro chan'ter (Gr. trecho , run), a 
part of an insect’s leg between 
the coxa and femur. 

Tym'pa num (Gr. tympanon , a 
drum), an ear-drum. 

Ven'tral (Lat. venter, the belly), 
pertaining to the belly, the part 
opposite the back. 



CHAPTER V. 


BUTTERFLIES AND MOTHS WITH THEIR 
PROTECTIVE DEVICES 

Directions for Work. Watch the caterpillars which 
have been collected in accordance with the directions 
previously given. Record the changes that occur. 

How many segments of the caterpillar have legs ? 

How many of these legs are jointed ? 

If the jointed legs are attached only to the thorax, 
how many segments has the thorax ? 

Does the caterpillar have eyes ? antennae ? palpi ? 

Do you find mandibles and maxillae ? 

Some of the caterpillars will change to chrysalids 
soon after collecting. 

In one of these chrysalids can you find head, thorax, 
and abdomen ? 

Is the chrysalis capable of any movement ? 

Can you find antennae, eyes, or palpi ? 

Do you find wings or legs ? 

Can you see parts of any organs under the skin ? 

Collect several common yellow butterflies, or the 
white cabbage-butterflies. 

Where do you find them ? 

At what time in the day do they seem to be most 
active ? 

On what plants do they feed ? 

How do they take their food ? 

Notice how they fly and how they walk. 

How do they hold their wings when at rest ? 

Secure some eggs, if possible, and watch their 
development. 


45 


46 


ANIMAL ACTIVITIES. 


The Prepared Specimen. Examine the butterfly 
after it has been killed, and write the resemblances 
and differences for butterfly and grasshopper as in the 
case of grasshopper and cricket. Consider all the 
points noted concerning the grasshopper. Consider 
the stages of growth. 

Study with care the coiled tongue, or proboscis. 
Uncoil it and find out how it is used. 

Remove the dust from a part of the wing. Is this 
part of the wing now colored ? With a microscope 



Fig. 46.—Antennae of Lepidoptera. A, of butterflies; B, of moths. 

note the shape of the particles of dust (scales). Note 
also how they are arranged on the wing. 

Measure the spread of the wings, the length and 
width of the anterior wings and of the posterior wings, 
the length of the body, and the length of the antennae. 

Describe the color above and below, and state the 
color and location of the markings you find. 

Notice the color of the feet, the antennae, and the 
eyes. 

Read the description of this butterfly in a good refer¬ 
ence book, and compare your own observations witl 
those there recorded. 








BUTTERFLIES AND MOTHS . 


47 


Write a description of a butterfly whose name is 
unknown to you. 

Write a description of a moth. 

Summary of Drawings, (a) The wings as seen 
from above when fully extended. 

(< b ) Side view of butterfly with wings closed. 

( c ) Side view of head—enlarged—showing proboscis 
and eye. 

( d ) Imaginary cross-section of proboscis. 

( e ) Larva, pupa, and imago of some butterfly not 
figured in the text-book. 

(/) The scales from a butterfly’s wing as seen with 
a microscope. 

(g) A portion of a wing, showing the arrangement 
of the scales. 

How to Tell Moths from Butterflies. Butterflies 
and moths are much alike. They may generally be 
distinguished by the fact that the butterfly has knobbed 
antennae, holds its wings erect in repose, and flies more 
often in the daytime. The moths often have feathered 
antennae, fold their wings horizontally over the back 
when at rest, and more often fly at night. 

Metamorphosis. The internal structure of the 
butterfly closely resembles that of the grasshopper, but 



a striking difference appears in its metamorphosis, or 
the change it undergoes during its period of growth. 
The young grasshopper when it emerges from the 
egg looks much like the adult insect; from which it 
differs chiefly in its smaller size and in possessing 
smaller wings. A series of changes like that observed 
in the case of the grasshopper is spoken of as incom- 



4 8 


ANIMAL ACTIVITIES. 


plete metamorphosis. On the other hand, there 
emerges from the egg of the butterfly a worm-like 
animal totally unlike its parents, who, could they 
see their offspring, would doubtless disown it. This 



Fig. 48.—Some Larvae of Lepidoptera. 


larva, as we have seen, has biting mouth-parts, fit¬ 
ting it to subsist on the leaves of plants. It eats 
voraciously, consuming many times its weight of food 
during its short life, and increasing rapidly in size. It 



Fig. 49.—Some Cocoons and Chrysalids. 


moults from time to time as its skin becomes too 
small for its fast-growing body. During this period 
of its life it is usually a destructive pest. The ravages 
of many caterpillars are already too well known. 





BUTTERFLIES AND MOTHS . 


49 


Finally, the larva seems to have eaten enough. It 
brings to a close its life of unceasing feeding and pre¬ 
pares for a period of sleep. Often it spins a silken 
cocoon in which it rests throughout the winter; some¬ 
times it hangs by a single thread to a rock or fence- 
rail, its exoskeleton making a beautiful chrysalis 
ornamented with spots 
of burnished silver, jet, 
and gold; again it buries 
itself in the ground to 
await the genial warmth 
of returning spring. In 
any case it takes no 
food and seldom moves, 
but within its body 
changes progress, until 
the full-grown butterfly 
or moth breaks through 
the hard case of the 
pupa, stretches and 
dries its wings for a 
short time, and flies 
away for its brief period 
of aerial life. 

The full-grown but¬ 
terfly, or imago, no 
longer eats the coarse 
food familiar to its lar¬ 
val stage. In fact, it 
could not do so if it 
would, for its mouth is 
no longer fitted for biting, but is provided with a long 
proboscis with which it sucks honey from its favorite 
flowers. This series of changes is known as com¬ 
plete metamorphosis (Fig. 50). 

Structure of the Proboscis. The proboscis is a 
curious organ and well repays careful study. It is 
composed of two long half-tubes which are produced 



Fig. 50.—A Cabbage-butterfly, «, 
larva; b, pupa; c, egg; d , imago. 






50 ANIMAL ACTIVITIES. 

by the elongating of the maxillae of the caterpillar 
while it is in the pupa stage. These join by their 

edges to form a complete 
tube which the butterfly can 
coil or uncoil at will and in¬ 
sert in the flower on which 
it feeds. At the upper part 
of this proboscis there is a 
pump-like cavity provided 
with a valve. When this 
enlarges, the tip of the tube 
being inserted in the cup of 
honey, the liquid flows up 
the tube and fills the cavity. 
The cavity then contracts 
under the influence of the 
surrounding muscles. This 
causes a pressure which 
compels the valve to close 
and forces the honey for¬ 
ward into the stomach (Fig. 51). 

Depositing Eggs. At the adult period of its life, 
however, the butterfly is not a great eater. Its most 
important function, now, is reproduction, and for this 
purpose the female butterfly searches for the plant 
which will furnish suitable food for her young brood 
of caterpillars and deposits there her eggs, dying soon 
after the performance of this function. The eggs of 
the clover-butterfly are placed upon the under side of 
clover-leaves, one to each leaf. The eggs of the tent- 
caterpillar, so common on apple- and cherry-trees, are 
laid in large clusters glued to the branch of the tree 
by a gummy substance produced by the moth deposit¬ 
ing the eggs. In many cases the eggs of butterflies 
and moths show beautiful markings when studied with 
the aid of the microscope. 

Butterfly Enemies. If all the eggs of all the butter¬ 
flies and moths should be allowed to reach maturity 



Fig. 51.—Head of a Moth. 
a , upper lip; b , mandibles; 
c , proboscis; d, under lip; <?, 
antennae; f, eye. 



BUTTERFLIES AND MOTHS. 51 

during - a single season they would kill all vegetation 
on the earth. The number of eggs deposited is 
enormous, and the few which reach the caterpillar 
stage make great havoc with our orchards, and often 
with our shade-trees. The gypsy-moth alone, in spite 



Fig. 52.—The Kallima, natural size. Drawn by 
A. E. Sanford. 


of great efforts, still does much damage. The number 
and activity of caterpillar and butterfly enemies in 
most cases holds them in check and allows only a 
small number to come to maturity. Both two-winged 
and four-winged flies deposit their eggs on the larvae 
or pupae of butterflies or moths. When these eggs 
hatch they produce larvae which feed on the fat and 
muscle of their involuntary host and finally destroy its 
life. A living, but nearly dead, caterpillar bearing on 


5 2 


ANIMAL ACTIVITIES. 


its back a great number of pupa-cases of such flies is no 
uncommon sight (Fig. 67). Birds, too, devour im¬ 
mense numbers of insects in all stages of growth. 
Doubtless they would kill and eat all the insects were 
it not for the fact that many of them are so wonder¬ 
fully protected by their color or shape, or both. 

Protective Coloration. A butterfly or moth when 
pursued often disappears as if by magic, and only the 
most careful search reveals its presence. Then it is 



Fig. 53.—Catocala Nupta. 


seen that the insect has been rendered invisible, not 
by the helmet of Perseus, but by its resemblance to 
some natural object common in its vicinity. The 
Kallima , a large and brilliant butterfly of India, folds 
its wings and alights on a branch. The folding of the 
wings conceals every brilliant color, and the under side 
of the wing, which is now alone visible, resembles so 
accurately a leaf that a bird could find it only with 
great difficulty (Fig. 52). 

Some of our common moths, belonging to the genus 
Catocala , have outer wings so closely resembling the 
bark of birch-, poplar-, or willow-trees that when they 
alight on one of these trees they cannot be seen by a 
casual observer. Other cases of protective coloring are 
to be met with at every turn in the study of Zoology, 
and it is a part of the work of the student to find and 
describe them. 


BUTTERFLIES AND MOTHS. 


53 


Mimicry. The common milkweed-butterfly has a 
disagreeable odor and probably a disagreeable taste. 
On this account it is not a favorite food for birds. The 




Fig. 54.—The Milkweed-butterfly, a , dorsal view; b, ventral view. 
One half natural size. Drawn by A. E. Sanford. 

a b 



Fig. 55.—Limenitis Ursula, a, dorsal view ; b, ventral view. One half 
natural size. Drawn by A. E. Sanford. 


Limenitis Ursula , a smaller butterfly, furnishes a dainty 
morsel for bird palates. It would soon be exterminated 
were it not for the fact that it so closely resembles in 
color and markings the milkweed-butterfly, to which 


54 


ANIMAL ACTIVITIES. 


it is not closely related in structure or in mode of 
growth (Figs. 54 and 55). 

Such imitations of other animals less likely to suffer 
from enemies are common throughout the animal king¬ 
dom. In these cases, neither the mimic nor the animal 
mimicked is supposed to act consciously. No intelli¬ 
gence on the part of the animal itself is shown by such 
mimicry, for even if it intelligently wished to change 
its color, no butterfly could do so. 

The theory which is now generally believed by 
scientists to account for these protective devices and 
the thousands of others that have been observed may 
be briefly illustrated by considering the family history 
of the moth whose wings resemble birch-bark. 

Natural Selection. It is supposed that the earlier 
members of this family did not have the outer wings 
so marked, but that from a brood of caterpillars there 
hatched moths like the parent moths, yet varying to 
some extent on account of unknown causes. Some of 
these varying moths had markings on the outer wings 
which made them resemble in some slight degree the 
birch-tree on which they were accustomed to alight. 
It is evident that these protected moths would be less 
likely to be eaten than those not resembling the birch- 
tree; hence they would be preserved to deposit eggs, 
while their less fortunate brothers and sisters would be 
eaten. The next brood of moths, resembling their 
parents as they must, would be likely to include a 
greater number of protected individuals, and probably 
some even better protected than their parents. Those 
best protected would be allowed to produce offspring, 
while the less favored would be destroyed. In this 
way after many generations the protective resemblance 
becomes more and more pronounced. This process 
has been called “natural selection”. It is thought 
to explain many of the changes which have taken place 
in the history of both animals and plants. It is easy 
to see that there is really no rational selection on the 


BUTTERFLIES AND MOTHS . 


55 


part of the animals themselves. The name was given 
because the process resembled somewhat the process 
by which bird-fanciers obtain different varieties of 
pigeons by “selecting” birds with peculiar markings 
for breeding purposes, or by which gardeners obtain 
new varieties of flowers by continually “selecting” 
the few having desirable peculiarities and obtaining 
seeds from these for the production of more and more 
desirable plants. In natural selection there is no bird- 
fancier and no gardener. On this account the process 



Fig. 5 6 a. —Moth at Rest. Fig. 56^.—Butterfly at Rest. 

has been spoken of as the “survival of the fittest”. 
In this case the “ fittest ” is the individual best adapted 
to his surroundings and best protected in every way. 
In these days the student of animals or plants is con¬ 
stantly on the watch for new illustrations of adaptation 
to surroundings on the part of living organisms. 

Questions. 1. How do moths differ from butterflies 
in structure and in habits ? 

2. What are the differences between complete and 
incomplete metamorphosis ? 

3. How much can a butterfly see ? 

4. How much can a caterpillar see ? 

5. Do either caterpillar or butterfly have a sense of 
smell ? of hearing ? 

6. What are some enemies of butterflies ? 



56 


ANIMAL ACTIVITIES. 


7. How are butterflies protected ? 

8. Does the pupa of a butterfly breathe ? 

9. Do you know any common animals which are 
protected by their color ? 

Topics for Reports. The Silk-worm. The Gypsy- 
moth. The Clothes-moth. The Life-history of Cecro- 
pia. The Metamorphosis of Lepidoptera. How to 
Destroy the Most Injurious Lepidoptera. Insects as 
Food. 


VOCABULARY. 


A'nus (Lat. anus, a ring), the 
opening of the digestive canal 
opposite the mouth. 

Chrys'a lis (Gr. ckrysos , gold), the 
naked pupa of a butterfly. 

Cos tal (Lat. costa, a rib), the ante¬ 
rior part of a wing. 

Co coon' (Lat. concha, a shell), the 
silken covering of a pupa. 

Gan'gli on {Gr. ganglion, a tumor), 
a nerve-mass. 

Haus tel'late (Lat. hausirum, a 
water-drawing machine), having 
mouth-parts fitted for sucking. 

I ma'go (Lat. wiago, likeness), the 
adult insect. 

Lar'va (Lat. larva, a mask), the 
stage of metamorphosis immedi¬ 
ately succeeding the egg. 


Man di bu late (Lat. mando, chew), 
having mouth-parts fitted for 
biting. 

No'tum (Gr. notos, back), the dor¬ 
sal surface. 

Pri'ma ry wings (Lat. primus , 
first), the first pair of wings. 

Pro bos'cis (Gr. pro, before, and 
bosko, feed), the sucking tongue 
of a butterfly. 

Pu pa (Lat. pupa , a doll), the stage 
of metamorphosis after the larva. 

Sec'on da ry wings (Lat. secun- 
dus), the second pair of wings. 

Vein (Lat. vena, a blood-vessel), 
one of the vein-like ribs of an 
insect’s wing. 

Vein'ules, branches of veins. 



CHAPTER VI. 

SOME INSECTS CLASSIFIED. 

The Bluebottle Fly. Expose a piece of fresh meat 
in a sunny place for a short time and these flies will 
collect on it. Capture some of the flies and observe 
them carefully. 

How does the fly feed ? You can study the mode 
of feeding of the common house-fly by fastening a piece 
of sugar to a slide and placing it under a microscope 
in a place where flies are plentiful. 

What kind of food does a common house-fly prefer ? 
How do you know ? 

Devise an experiment for determining what kind of 
food the house-fly particularly likes. In experiment¬ 
ing with foods try sugar, honey, salt, pepper, water, 
and other substances. 

Does sight or smell seem to guide the fly to its food ? 

How does a low temperature affect flies ? How do 
you know ? 

Plow do the flies make their buzzing ? 

Keep a few bluebottle flies under a tumbler with a 
bit of meat until eggs are deposited. Remove the flies 
and watch the development of the eggs. Does the fly 
have complete or incomplete metamorphosis ? 

How many wings has the fly ? 

How many segments has the fly’s abdomen ? 

See if you can find a winglet behind the wing. 

Using a lens, do you find a pair of balancers behind 
wing and winglet ? 

Is one of the segments of the thorax larger than the 
rest ? 


57 


ANIMAL ACTIVITIES. 


58 


Do you find spiracles on either thorax or abdomen ? 
Do you find eyes and ocelli ? 

Do you find antenna ? 

Write resemblances and differences for fly and grass¬ 
hopper. 



Fig. 57.—Larva and Pupa 
of the House-fly. b, larva 
[magnified)', c, pupa [mag¬ 
nified). 


Fig. 58. — Right 
Winglet o f 
Bluebottle 
[magnified). 


Fig. 59.—Balancer 
of Bluebottle 

(magnified . 


Summary of Drawings, (a) A fly as seen from 
above with the wings extended at right angles to the 
body X 5 - 

( b ) The larva and pupa of a fly X 5- 
(r) One wing X 5- 

(d) A balancer much enlarged. 

( e ) One antenna as seen with the microscope. 

(/) One leg and foot as seen with the microscope. 












SOME INSECTS CLASSIFIED . 


59 



Fig. 6o.—P ortion of a Fly’s 
Foot {magnified). 



Fig. 6i.— Side View of Proboscis, 
partly opened. basal division; 
c , central division; /, labella; m , 
maxillary palpi. 



Fig. 62 Head of Bluebottle. a , antennae; e, eyes; m, maxillae; /, 

proboscis ( magnified ). 







6o 


ANIMAL ACTIVITIES. 


(£•) A foot highly magnified, showing the two claws 
at the end of the last segment and the sucking-disks 
by which the fly walks on a ceiling. 

( h ) The proboscis as seen with the microscope. 

The Colorado Beetle. This beetle is often called 
the potato-bug or potato-beetle. Its destructive ravages 
are well known. A visit to a potato-field anywhere 
while the plants are growing will commonly provide 
the collector with an abundance of specimens in all 
stages of growth from the egg to the adult. Look for 
eggs on the under side of a leaf. The pupa stage is 
spent underground, and specimens are more difficult 
to find. Keep in formalin. 

Examine a living beetle. 

Notice how it eats, how it walks, and how it flies. 

See if you can make out how its wings are folded. 

How does the folding compare with the folding of 
the wings of a grasshopper ? 

Notice the eggs and the various stages of growth. 

How many segments has the beetle’s abdomen ? 

Of how many segments is each foot composed ? 

Examine a dead specimen with care and write resem¬ 
blances and differences for beetle and grasshopper. 

The Dragon-fly. Near fresh-water ponds and streams 
adult dragon-flies may be easily caught. The larvae 
are usually plentiful where decaying leaves furnish 
food for the small animals on which they live. The 
imago may be mounted like a butterfly and then ex¬ 
amined. 

How many wings ? 

Are the wings folded ? 

Are the wings alike ? 

How does the veining compare with that of a fly’s 
wing ? 

Is the head easily movable ? 

How does it compare with the other insects you have 
studied in regard to the size of its eyes ? 

Has it ocelli ? 


SOME INSECTS CLASSIFIED. 


61 


How do the mouth-parts compare with those of a 
butterfly ? with those of a grasshopper ? 

Do you find toothed mandibles ? 

Are the segments of the thorax of equal size ? 

Are the legs strong or weak ? 

How does the abdomen compare with that of the 
grasshopper ? 

How many segments has the abdomen ? 

Do you find spiracles ? 

Examine one of the larvae and tell how it differs from 
the imago. 

Examine with particular care the mouth of one of 
the larvae. 

Summary of Drawings, (a) The imago as seen 

from above X 2. 

(( b ) One antenna, magnified (microscope). 

([c ) Side view of mask of larva, magnified (micro¬ 
scope). 

(d) Side view of larva X 3- 

Mud-wasps can be easily collected in almost any 
locality. Obtain specimens and write resemblances 
and differences for wasp and beetle. 

Squash-bug. Write resemblances for squash-bug 
and potato-beetle. 

Resemblances. The number of insects is so great 
that it is practically impossible for one person to learn 
their names, to say nothing of being able to know their 
habits and structure. 

When, however, one has become familiar with only 
a limited number of forms, certain resemblances thrust 
themselves upon the attention. These points of like¬ 
ness are of great assistance in extending our acquaint¬ 
ance, for when we know one insect well we have some 
knowledge which applies to all. If we hear of a new 
insect we at once suppose that it has those peculiarities 
which we have found common to all insects we know, 
and in so supposing we are not likely to be mis¬ 
taken. 


62 


ANIMAL ACTIVITIES . 




in 

<D 

CJ 

rt 

Oh 

in 

G 

d 


<v 

rG 


CG 

T 3 

G 

rt nj 
> T 3 

£ g 
<u 
.o 

in 

3 
O 


T 3 

<L> 

4-> 

CtJ 

.CJ 

*5 

C 

• *H 

Vh 

<U 

c 

c 

d 


> 

V 

!—I 

Oh 

in 

<u 

4-> 

o 

G 

OJ 
G 3 P 

4-> 

<U . 

G3 tU0 

•*-» G 

• *H 

c 

3 
in 


O 

u 


0^ 
o 
o 

V 

G 

Vh 

3 

O 

X 


V 

bj) 

d 

Oh 

d 

JU 

~3 


Wasp. 








Squash-bug. 








Beetle. 








Dragon-fly. 








Fly. 



■ 





Butterfly. 









J-i 

<v 

a, 

a 

o 

pC 

w 

C/3 

Oj 

»-. 

o 


o 

o 

«r 

<v 


c3 

in 

o 

+-> 

a3 

« 


>■ 

33 


JS 

I ^ 

C ^ 

3 *HH 

a o 


o) 

a 

o 


05 

bO 

c 


O 

nd 

c 

13 

33 

3 

d 

u 

<u 

rO 

£ 

3 


»H 

a 

05 

u 

•3 

<+H 

<L) 

• »—< 
Ih 

32 

T3 

3 

ci 


05 

two 

(U 


fc ° 

32 3 

£ .2 

d 

£ 


3 

rj 


<D 

Qh 

03 

JS 

05 

T3 

3 

d 

'v g 
32 £ 

£ S 

3 

£ 


3 

O 

£ 

bo 

3 
• ^ 

34 

o 

3 

05 

Jh 

o 

05 

bot! 

3 rt 
'3 Oh 

pq 


3 

H-> 

a; 


O 

a 

3 

• # 

in 

cn 

tH O 

O 33 
Ph 


<u 2 

HH 3 

o ^ 

U 


































































SOME INSECTS CLASSIFIED. 


63 


By comparing the notes we have already made we 
find that the insects so far studied have bilateral 
symmetry , jointed bodies , and jointed appendages , as 
legs and antennae. They have three parts to the body; 
head, thorax, and abdomen. All have six jointed 
legs, and in the adult stage one or both sexes are 
‘ usually provided with wings. Commonly two pairs of 
wings and a pair of compound eyes are present. 

An examination of the internal structure of insects 
shows a series of ganglia connected by nerves situated 
along the ventral portion of the body. Above this is 
found the digestive cavity, consisting of a tube more 
or less branched extending lengthwise of the body, 
from the mouth to the anus. Near the dorsal part of 
the body is found a large blood-vessel which performs 
the function of a heart. 

Breathing is carried on by means of spiracles con¬ 
nected with tracheae. Naturalists have agreed to call 
animals having these characteristics “ Insecta ”. 

Differences. But the class Insecta contains so many 
individuals that we readily see the necessity of classify¬ 
ing them in some way. The divisions of classes are 
called orders. If we can divide the class Insecta into 
orders we make our future study more systematic and 
more satisfactory in many ways. Such a classification 
must depend on differences as well as resemblances. 
If we should study the mouth-parts alone of the insects 
we have already examined, we could easily put them 
into two orders or subclasses, one comprising those 
insects which have biting mouth-parts and the other 
those which have sucking mouth-parts. This division 
is sometimes used, but for our purpose it will be 
better to find some differences which will give us a 
greater number of orders, and so -greater convenience. 

A mode of separation based on peculiarities of the 
wings has been much used, and the common names 
for some of the orders as now most often written 
attempt to describe peculiarities of wing-structure. 


64 


ANIMAL ACTIVITIES. 


But this scheme of classification seems too artificial, 
that is, too much like the classification of inanimate 
things like tables or chairs, which may be arranged for 
convenience into classes according to use or shape. 

The course of development from egg to adult is also 
an important factor in classifying living things, because 
it is thought to show better than anything else the 
natural relations or affinities, or we might say the 
blood-relations of animals: hence in classifying insects 
the matter of metamorphosis must be considered. In 
a superficial way we might divide insects into those 
having complete and those having incomplete meta¬ 
morphosis, or into those having terrestrial larvae and 
those having aquatic larvae; but more careful study 
shows that these differences alone are not sufficient for 
a clear and systematic classification, nor do they, 
alone, indicate relation by descent. In fact, it has 
been found that with the best of effort in the matter of 
classification, so many intermediate forms occur that a 
series of individuals rather than a few orders result. 

Still convenience demands a classification of some 
kind. Taking into consideration as many differences 
as possible, and ignoring some of the less obvious 
peculiarities, we may include all insects in nine orders: 


Lepidoptera. 

Hymenoptera. 


Name. 

Thysanura. 

Pseudoneuroptera. 


Orthoptera. 

Hemiptera. 

Neuroptera. 

Coleoptera. 

Diptera. 


Typical Insect. 

Springtails. 

Dragon-fly. 

Grasshopper. 

Squash-bug. 

Caddis-fly. 

Colorado beetle. 

House-fly. 

Butterfly. 

Bee. 


Characteristics of the Orders. We give below the 
characteristics of these orders, noting chiefly the facts 


SOME INSECTS CLASSIFIED. 


65 


concerning wings, mouth-parts, and metamorphosis. 
There are, of course, many insects which do not fall 
easily into one of the orders as we have defined them, 
but it must be remembered that no classification of 
living things can be made to include all individuals. 
Some authors make a greater number of orders of 
Insecta, but the list here given is thought to conform 
to the best usage of writers on natural history. 

Thysanura. These are small wingless insects with 
biting mouth-parts and incomplete metamorphosis. 

The Pseudoneuroptera have two pairs of wings, 
very nearly alike in most cases. Their wings are very 
thin and transparent and closely veined and not 
capable of being folded. The mouth-parts are fitted 
for biting and the metamorphosis is incomplete. 

The Orthoptera commonly have two pairs of wings, 
the under wings being folded like a fan, and protected 
by the outer pair. The jaws are strong and fitted for 
biting, and the metamorphosis is incomplete. 

The Hemiptera, though sometimes wingless, have 
more often two pairs of wings. In some hemiptera the 
outer wings overlap on the back, the overlapping half 
of each wing being thin and membranous, hence the 
name. The mouth-parts are fitted for sucking, being 
prolonged into a beak used for piercing. They have 
incomplete metamorphosis. 

The Neuroptera resemble the pseudoneuroptera in 
wings and mouth-parts and have complete meta¬ 
morphosis. 

The Coleoptera have hard outer wings called elytra 
which protect the inner, gauzy wings, which are folded 
both lengthwise and crosswise. The mouth-parts are 
fitted for biting and the metamorphosis is complete. 

The Diptera have only two wings. The mouth- 
parts are fitted for sucking and the metamorphosis is 
complete. 

The Lepidoptera have four wings covered with 
scales. The wings do not fold. The mouth is fitted 


66 


ANIMAL ACTIVITIES. 


for sucking, having a long proboscis formed of the two 
maxillae. The metamorphosis is complete. 

The Hymenoptera have four membranous wings 
with few cross-veins, the fore and hind wings being 
commonly hooked together for flight. The mouth- 
parts are fitted for both sucking and biting and the 
metamorphosis is complete. 

Karnes of Insects. Animals, like plants, are desig¬ 
nated in scientific works by two names, the first the 
name of the genus, and the second the name of the 
species. Thus, Danais archippus means that the 
butterfly bearing that name belongs to the genus 
Danais and the species archippus. We also distin¬ 
guish men by using two names. Stuyvesant, Peter, 
as found in a directory, means that the man in question 
belongs to the family Stuyvesant, and that he is the 
particular member of that family known as Peter. 

Questions. How does the grasshopper differ from 
all the other insects studied ? 

How does the butterfly differ from the beetle ? from 
the dragon-fly ? from the other insects studied ? 

How does the fly differ from the other insects ? 

How does the beetle differ from the other insects ? 

How does the squash-bug differ from the beetle ? 
from the grasshopper. 

How does the wasp differ from the fly ? from the 
other insects studied ? 

How does the dragon-fly differ from the wasp ? from 
the butterfly ? 

In what respects do all the insects studied resemble 
one another ? 

Topics for Reports. House-flies. Insects in Brooks. 
Agricultural Ants. Insects in Ponds. Earwigs. The 
Cicada. Insects in Houses. Insects on Apple-trees. 
How to Prepare Insects for Cabinets. How to Kill 
Injurious Insects. Length of Life among Insects, 
Insect Lriends. Sounds Made by Insects, 


SOME INSECTS CLASSIFIED . 


67 


VOCABULARY. 


Bal'an cer (Lat. bi, two, and lanx, 
dish), one of the poisers of a 
dipterous insect. 

Col e op'te ra (Gr. koleos, sheath, 
and pteron , wing), beetles. 

Dip'te ra (Gr. di, two, and pterori), 
two-winged insects. 

El'y tron, pi. elytra (Gr. elytron, 
a shield), a thickened fore-wing 
of an insect. 

Ge'nus, pi. genera (Lat. genus , a 
race), a group of animals or 
plants commonly made up of 
two or more species. 

Hal'ter, pi. halteres (Gr. halteres, 
jumping weights), a balancer of 
one of the diptera. 

Hem ip'te ra (Gr. henti , half, and 
pteron), an order of insects in¬ 
cluding the true bugs. 

Hymen op'te ra (Gr. hymen , a 
membrane, and pteron), an order 
of insects including bees and 
wasps. 

In sec'ta (Lat. prefix in, and seco, 
to cut), a class of Arthropoda 
including all true insects. 


Lep i dop'te ra (Gr. lepis , a scale, 
and pteron ), an order of insects 
including butterflies and moths. 

Neur op'te ra (Gr. neuron , nerve, 
and pteron ), the name of an 
order of insects. 

Or'der (Lat. ordo , order), one 
of the divisions into which 
classes of plants or animals are 
arranged. 

Or thop'te ra (Gr. orthos, straight, 
and pteron), an order of insects 
including grasshoppers. 

Pseudo neur op'te ra (Gr. pseu- 
dos, false, and neuroptera), the 
name of an order of insects dif¬ 
fering from neuroptera in hav¬ 
ing incomplete metamorphosis. 

Spe'cies (Lat. species, outward ap¬ 
pearance), a subdivision of a 
genus. 

Thy sanu'ra (Gr. thysanos, fringe, 
and oura, tail), the name of an 
order of small insects. 

Wing'let, a small winglike fold 
behind the anterior wing in the 
Diptera. 



CHAPTER VII. 


A CHAPTER OF LIFE-HISTORIES. 

The Milkweed-butterfly. In speaking of protective 

coloring we have already mentioned the large and 
beautiful butterfly commonly known as the milkweed- 
butterfly. It is known to scientists as the Danais 
archippus or sometimes as the Anosia plexippus. On 
account of its large size, great beauty, and very general 
distribution, it has been much studied and its life-his¬ 
tory is well known. 

The female butterfly deposits her eggs one by one 
on the under side of milkweed-leaves. These eggs 


when examined with 
the microscope are 
seen to be very regu¬ 
larly carved in a beauti¬ 
ful and delicate pattern. 
The shape of the egg is 
shown in Fig. 63. 



In a few days a little 
black-headed caterpil¬ 
lar, perhaps a tenth of 
an inch long, emerges 
from the egg, eats its 


Fig. 63.—Eggs of Milkweed-butterfly. 
a, single egg, magnified; c, eggs on 
leaf, one half natural size. After 
Riley. 


empty shell for breakfast, and dines upon the milk¬ 
weed-leaf, on which it continues to feed for several 
weeks. At the end of one week, having eaten so much 
and grown so fast that its skin can no longer hold its 
body, it spins a bit of silk upon the leaf, waits until its 
coat splits down the back and then crawls out of the 


68 



A CHAPTER OF LIFE-HISTORIES. 


69 


slit thus made, a larger and handsomer caterpillar. 
It moults in this way twice more, and at last looks like 
Fig. 64, having a pair of horns at each end of its body 
and being striped with black, white, and yellow. 

It will be noticed that its first three pairs of legs are 
jointed and furnished with claws. The other legs, ten 
in number, are merely 
fleshy prolongations of 
the skin, provided with 
suckers or hooks to aid 
in crawling. These are 
called pro-legs, to distin¬ 
guish them from the three 
pairs of jointed legs com¬ 
mon to all Insecta. Its 
mouth is provided with strong mandibles, and its 
digesting power is enormous. The caterpillar has now 
reached a length of two inches. After a little time it 
again becomes restless, leaves the plant on which it 
has so far lived, and lodges on a neighboring fence or 
stump. Here it spins a little silk, entangles its hind 
legs in the threads thus produced, and hangs head 
downward for a day and a night. Its skin then splits 
along the back and the caterpillar performs the difficult 
feat of crawling entirely out of its old covering without 
the use of legs or mandibles, for these 
disappear with the old skin. The little 
spike at the end of its tail is fastened 
into the web of silk, and its body sus¬ 
pended thereby for a period of rest. The 
skin hardens and the rich ornamentation 
FlG ; Pu P a of green, black, and gold appears. We 
butterfly, one a° not wonder that it is called a chrysa- 
half natural Hs (Fig. 65). 

size. After There is now no mouth for feeding, 
for the mouth-parts are undergoing a 
wonderful change just beneath the skin. The maxillae 
elongate to form a proboscis, the wings appear and 




Fig. 64. — Larva of Milkweed- 
butterfly, one half natural size. 
After Riley. 


7 ° 


ANIMAL ACTIVITIES. 


may be seen undeveloped within the chrysalis, as may 
also the antennae, the legs, the segments of the thorax 
and abdomen, and even the spiracles. At this time 
the young butterfly must live by using the stored-up 
energy developed by its enormous appetite in the 
larval stage. The change now going on is termed 
pupation. 

Again moulting occurs, and the imago emerges. 
At first it is soft and flabby, but the blood pumped into 
the baggy wings quickly distends them and they dry 
and harden in the sunlight. The body soon attains its 
full strength and the insect flies away to enjoy a life 
entirely different from its previous phases of existence. 
Now it rejoices in two pairs of large and strong wings 
covered with beautiful scales arranged in regular pat¬ 
terns. It sucks honey from flowers by means of its 
long coiled proboscis. This interesting piece of 
machinery has already been described. It is doubtful 
if this magnificent aerial creature, leisurely floating in 
mid-air, or bravely buffeting the winds, and sometimes 
sipping a bit of nectar, would recognize one of its 
brothers or sisters in either its gormandizing larval 
stage or its inactive pupal condition. Indeed, the 
graceful mother seems neither to recognize nor to care 
for the offspring crawling from the eggs she deposits 
from day to day. 

Our milkweed-butterfly lives much longer than most 
of her lepidoptera relatives while in the imago stage. 
She even migrates when autumn comes and with others 
of her kindred seeks a warmer climate for the winter. 
Some of those which do not migrate hide in sheltered 
crevices to emerge in the spring battered and frayed, 
but ready to deposit eggs for the new broods which are 
to people the air of the coming summer. 

The Cricket. The common black cricket so often 
seen in the fields and about our gardens in the late 
summer and during the autumn is known as Gryllus 
abbreviatus. His pleasant chirp attracts us to an 


A CHAPTER OF LIFE-HISTORIES. 


71 


examination of his ways. Putting him under a tumbler 
over a flower-pot filled with earth, and feeding him 
with bits of apple or potato and sometimes a little 
clover, we may easily observe his movements. If we 
are looking at the male we must watch for the source 
of his cheerful music, for the males do the talking 
among crickets. We shall see, when the shrill sound 
is made, that the outer wings are raised a little and 



Fig. 66 .—Female and Male Aphis. 


moved rapidly from side to side. A careful examina¬ 
tion shows on the inside of the membranous wing-cover 
a vein extending diagonally across the wing and fur¬ 
nished with teeth like those on the corner of a file. 
On the other wing-cover, near its inner margin, there 
is a hardened part which scrapes over the file, causing 
it to vibrate. The membranes of the wing re-enforce 
the vibration. Thus its voice comes not from its throat 


72 


ANIMAL ACTIVITIES. 


but from its back. In this respect it resembles many 
other insects. 

If we are looking at the female cricket we are struck 
with the length and size of the ovipositors, which con¬ 
sist of a pair of grooved appendages which fit together 
to form a long tube with a sharpened point. In the 
autumn the cricket bores a hole in the ground with 
these sharp points and deposits her eggs, where they 
remain through the winter. In the spring the warmth 
of the sun causes them to hatch and the little crickets 
appear. Here we have something very different from 
the hatching of tl^e milkweed-butterfly’s egg. No 
caterpillar appears here, but a tiny cricket, much like 
its mother, but lacking wings. These little crickets 
moult from time to time, at each moult growing more 
like their parents, until about midsummer, when they 
attain their full size. Before winter they die. 

The Aphis. Plant-lice are very familiar pests, 
whose ravages on the leaves of rose-bushes are well 
known. There are many kinds of these little destroyers 
inhabiting as many kinds of plants. They are called 
Aphides , any one insect being an Aphis. 

A single aphis with its beak stuck into the juicy part 
of a leaf, from which it never moves unless forced to 
do so, constantly filling its stomach with sap, seems, 
indeed, a mere glutton, but the whole brood of aphides 
when watched for a summer are a wonder-working 
community. The laboratory for the study of these 
strange creatures is ready-made everywhere. Wher¬ 
ever rose-leaves grow, a lens will reveal the happenings 
we are about to relate. 

In the month of October in temperate climates the 
wingless female deposits her eggs about the buds of 
rose-bushes, so that when these develop into leaves 
and branches in the coming spring the young aphis 
may have at hand a bountiful supply of rich food. 
Here the egg stays until the warm sun of March or 
April assists in the process of hatching. 


A CHAPTER OF LIFE-HISTORIES. 


1 3 


There hatch from these eggs a brood of females, very 
small at first, but, after several moultings, as large as 
their mothers, and resembling them in many ways. 
No males are hatched from these winter eggs. The 
leaf soon becomes covered with a swarm of female 
insects. Indeed, there are no fathers in these armies 
of pigmies. They produce no eggs, but proceed to 
fasten their beaks in a juicy spot and eat and reproduce 
in a most marvelous manner. 

From the abdomens of these strange mothers there 
issues day after day a numberless horde of children like 
themselves. These children grow from the mother as 
buds grow on plants, and then break away to lead an 
independent life. Each tiny bud in a few days becomes 
a mother in the same way, and shortly, from a single 
egg, thousands of wingless mothers sit side by side, 
sucking sap and budding out young with remarkable 
speed. If a man should live a hundred years and 
count at the rate of one a second, he could not begin 
to count in his hundred years the progeny of a single 
aphis for a month. 

Now and then winged forms appear, and sometimes 
an aphis goes through something like a larval and 
pupal stage, while the colony keeps on increasing with 
incredible rapidity by the budding of generation after 
generation. This reproduction without males is called 
parthenogenesis . 

Toward autumn winged males are produced, and 
again the cycle of existence is renewed. 

In studying the life-history of the aphis one should 
notice the relations existing between ants and aphides. 
As the aphis sucks the sweet sap from its shrub it 
obtains an excess of sugar; that is, in order to get all 
the muscle-forming food it requires it must eat more 
sugar than it needs. This excess of sugar is known 
as honey-dew, and it often covers the leaves with a 
sticky film. It comes from two projections on the end 
of the abdomen of the aphis. This honey-dew, not 


74 


ANIMAL ACTIVITIES. 


needed by the aphis, is relished by other insects, 
notably the ants, which may be seen stroking the pro¬ 
jections from which the honey-dew exudes and eagerly 
eating the sweet fluid. 

So much do the ants appreciate this honey-dew that 
they take great pains to care for their friends the 
aphides, in many cases herding them as men herd 
cows, and sometimes carrying their attentions so far 
as to take the winter eggs of their cows into their own 
houses to keep them from frost and enemies. With 
returning spring these eggs are taken out again and 
placed upon their proper food-plants to hatch in the 
warmth of the sun and produce another colony of 
aphides. 

The Ichneumon-fly. Teachers of Zoology fre¬ 
quently have brought to them for identification and 
explanation a caterpillar, having his back covered with 
a mass of silken cocoons. If we wait for the cocoons 
to hatch we may see coming from each a black four¬ 
winged insect from one eighth to one fourth of an inch 
in length. The female of this insect, when mature, 
deposits great numbers of small eggs directly under 
the skin of a living caterpillar. These eggs soon hatch 
into small grubs or maggots which live on the fat of 
their host, not interfering with his digestive apparatus 
or other vital organs. After a time the full-grown 
larvae bore holes through the caterpillar’s skin, come 
out of their living prison and spin cocoons, fastening 
each to the caterpillar’s back by a thread of silk. In 
these cocoons the pupa stage is passed and the adult 
insect gnaws his way out to begin another cycle. 
These insects are often called microgaster-flies. They 
belong to the order Hymenoptera (Fig. 67). 

The Sand-wasp. Still another method of preparing 
fresh meat for the young has been invented by some of 
the wasps. These wasps catch a caterpillar, a spider, 
or some other insect, and sting him in such a way 
in the thoracic ganglia that the victim becomes 


A CHAPTER OF LIFE-HISTORIES. 


75 


paralyzed but is not killed. The wasp then drags her 
prey into her hole, and deposits an egg on the motion¬ 
less but living insect, apparently knowing that death 
will not occur until her egg has become a larva and 
requires food. When the larva appears he finds his 
food still living, and makes it last until he is ready to 
assume the pupal condition. This is a remarkable 
insect adaptation for the preservation of food. 

There are many of these wasps. Some of them live 
in holes in the ground, which they stop up and conceal 



Fig. 67.—A Microgaster Fly (; magnified ). r, larva of a microgaster in 
the caterpillar of a cabbage-butterfly. 


in very ingenious ways after the egg and its provender 
have been stored away. 

Others build their nests or cells of mud, enclosing 
the young and its food in earthen jars. 

A full-grown mud-wasp may be kept in confinement 
for a time and fed on sugar and water. Her mem¬ 
branous wings, four in number, are folded over her 
back when at rest, but during flight they are spread 
out and the fore and hind wings are fastened together 
in such a way by hooks and grooves tb^ f they appear 
like a single pair. 


7 6 


ANIMAL ACTIVITIES. 


The ovipositor differs from that organ as we have 
seen it in the cricket and grasshopper in having, in 
addition to the grooved sheath through which the eggs 
pass, a pair of lances which pierce the insect it wishes 
to paralyze or kill. The paralysis is probably caused 
by a bit of formic acid which is secreted by a small 
gland in the wasp’s abdomen and injected into the 
body of her victim. 

• The sting, then, in this case as in the bee and other 
hymenoptera, is a modified ovipositor. 

The care with which the wasp cleans its body and 
performs its toilet is worth noting. In fact, many 
things may be learned by watching one of these intelli¬ 
gent little workers. 

The Dragon-fly. To study insects which spend a 
part of their life in the water an aquarium is helpful and 
pays well for the trouble it costs. 

To study the young dragon-fly one should visit a 
pond or pool of fresh water, provided with a small net 
and a supply of fruit-jars. The young dragon-flies 
may be recognized by their flat square heads, their 
rudimentary wings, and their six strong legs. They 
frequent the bottom of the pool in which they live and 
their color protects them from observation, but careful 
watching will soon reveal their presence. One sweep 
of the net will sometimes bring several nymphs to the 
collector’s jar. One must at the same time collect 
some aquatic plants to keep in his aquarium, and also 
a supply of small insects for dragon-fly food. A little 
mud from the pool with some submerged sticks and 
leaves will furnish insect-food for several days, after 
which a fresh supply should be provided. With a little 
sand in the bottom of a jar, a few growing water-plants, 
and a supply of dragon-fly nymphs of varying sizes, we 
are ready to learn something of the life-history of the 
mosquito-hawks, as dragon-flies are sometimes called. 

While collecting the young, one is likely to see the 
adult females dipping the tip of the abdomen beneath 


A CHAPTER OF LIFE-HISTORIES. 


77 


the surface of the water in the act of depositing eggs. 
These eggs soon hatch into tiny nymphs, which live 
in the water, and, moulting from time to time, produce 
the various sizes found by the collector. 

If we compel a few of these nymphs to go without 
food for a day and then feed them with insects, we 
shall be able to watch the use of the strange mask 
which hides the face, or perhaps we should say the 
mouth. This mask is really a very strange develop¬ 
ment of the so-called lower lip, the structure of which 
may be understood by examining one of the nymphs 
and comparing it with the accompanying sketches 
(Fig. 68). After all, it is not so much a mask as a 



Fig. 68.—The Dragon-fly. A , larva; B, pupa; C, dragon fly emerg¬ 
ing from pupa-case. 


formidable grasping organ capable of reaching suddenly 
forward, seizing an unsuspecting victim, and dragging 
him back to the hard mandibles. 





78 


ANIMAL ACTIVITIES. 


Breathing of a Dragon-fly Nymph. An insect 
living in the water must breathe, and it is interesting 
to observe how insects which have chosen an aquatic 
life have adapted their breathing-organs to the medium 
in which they live. The dragon-fly larva does not 
trouble himself to come to the surface for air, but 
simply takes his oxygen from the air dissolved in the 
water. The spiracles which would allow water as well 
as air to enter the breathing-tubes are closed and covered 
by the hard exo-skeleton, but the tracheae or breath- 



Fig. 69. —The Imago of a Dragon-fly. 


ing-tubes, like those in the grasshopper, convey the 
air throughout the body. To get the air, the water is 
drawn in through the anal opening, where it comes in 
contact with some modified air-passages which have 
somewhat the function of gills. In these air-passages 
the carbon dioxide and other impurities await the 
opportunity to pass by osmosis to the water, while the 
oxygen penetrates through the membranes into the 
breathing-tubes. If a fine stream of bright-colored 
liquid be put near a nymph by means of a small 
pipette the currents produced by the breathing may be 
seen. 








A CHAPTER OF LIFE-HISTORIES. 


79 


Possibly some of the larger nymphs in the aquarium 
may crawl up a stick or other object and, fastening 
their feet firmly, await their final metamorphosis from 
aquatic to aerial life. 

At this time the exo-skeleton of the nymph splits 
down the back and there emerges the beautiful creature 
we so often see hovering over the surface of streams 
and ponds. The two pairs of delicately veined wings 




Fig. 70.—Caddis-fly, Adult and Larval Cases. 

are never folded like those of the grasshopper or beetle, 
but remain extended even while the insect alights. 
The lower lip has lost its mask-like appendage, the 
mandibles are hard and toothed, the eyes are very 
large, the abdomen is long and tapering, the legs are 
small and bunched together for security in alighting. 
It is now a fine creature of wonderful agility and grace. 
Harmless to man and larger animals, it devours mos- 




8o 


ANIMAL ACTIVITIES. 


quitoes and other small insects, catching them on the 
wing with hawk-like flight and precision of aim. 

The dragon-flies belong to the pseudoneuroptera. 
By some they are put in a separate order, the odonata. 

Other Aquatic Insects. While collecting and 
observing the young dragon-flies one cannot help 
noticing the fact that many other insects spend a part 



Fig. 71.—The Growth of a May-fly. A , larva; B, pupa; C, imago. 


or the whole of their life in the water. It will be 
interesting to watch the young caddis-flies (Fig. 70), 
young may-flies (Fig. 71), the adult water-boatman 
swimming on his back with his legs modified to form 
oars (Fig. 72), the ditycus or large water-beetle carry¬ 
ing a bubble of air under his elytra and feathering his 
oars as he dashes through the water (Fig. 73), and 
the giant water-bug with powerful piercing beak and 




A CHAPTER OF LIFE-HISTORIES. 8l 

mighty fore legs for holding his victims while sucking 
their life-blood (Fig. 74). 

The Mosquito. Among aquatic insects the familiar 
mosquito or gnat deserves a paragraph. The female 
mosquito, which by the way is said to do all the biting 



Fig. 72.—A Water-boatman. A , in the water; B, while flying. 


and all the singing, leaves her eggs, sometimes two 
or three hundred in number, glued together in a sort 
of raft which floats upon the water (Fig. 75). In a few 
days the tiny larvae open the under side of the eggs 



Fig. 73.— Dyticus Marginalis. A , male; B, female. 


and descend into the water, where they swim rapidly 
about with a peculiar jerking motion. The large head 
is usually downward, always so while at rest near the 
surface of its pool. Just back of the head is a large 






































8 2 


ANIMAL ACTIVITIES. 


joint commonly called the body, and back of that the 
smaller joints of the abdomen. The end of the tail is 
double as shown in the figure. 
One projection is the insect’s 
propeller, and the other its 
breathing-tube, which it is 
constantly using when at 
rest, opening or closing at 
will the tiny valve at its ex¬ 
tremity. The mosquito larva, 
then, breathes air directly 
and does not take it from the 
water like the young dragon¬ 
fly. Like its mother, the 
larva is bloodthirsty and 
always hungry. At the end 
of about two weeks, after 
moulting several times, the 
larva changes to a pupa, 
bending its head under its 
body as seen in the figure and losing its mouth alto¬ 
gether, but retaining its power of active movement. 
The breathing-tube at the end of its body disappears 
and it now takes air by two tiny projections on its 
back. Finally, the pupa rises to the surface of the 
water and again moults, producing the adult mosquito, 
which uses its cast-off skin as a boat on which it floats 
until its wings are dry and it is ready to fly away. 
Should its frail boat capsize and wet its wings the 
mosquito would drown. It has been 
found that a little kerosene spread 
upon the water of stagnant pools 
will not only kill the egg-rafts as 
they float about but will also destroy 
the perfect insects as they emerge 
from their pupa-case boats. 

The imago now breathes, like other insects, by the 
spiracles along the sides of its body. It has but one 



Fig. 75.—The Egg- 
raft of a Mosquito. 



Fig. 74.—Mouth of a Bug. a , 
antennae; /, labium; m , man¬ 
dibles and maxillae; e , eye. 





A CHAPTER OF LIFE-HISTORIES . 


83 



Fig. 76.—The Life-history of a Mosquito, 










































8 4 


ANIMAL ACTIVITIES. 



pair of wings, and its mouth-parts are fitted for suck¬ 
ing. The mouth of the male mosquito is adapted for 
sucking honey from flowers and 
it leads a mild and peaceful life. 
The female mosquito, on the 
other hand, has, in addition to 
the proboscis for sucking blood, a 
number of sharp lances with which 
she pierces the skin of her victim. 
At the time of piercing she also 
injects an irritating fluid into the 
puncture (Fig. 77). 

The music made by the mos¬ 
quito is produced in two ways, 
first by the rapid movement of 
the wings, and second by the 
passage of air in and out of the 
spiracles. The humming thus 
made is thought to be heard by 
the male mosquito, whose ears 
consist of tufts of hairs on his 
antennae. These hairs are said 
to vibrate in unison with the tones made by the wings 
and spiracles of the female. Experiments seem to 
show that some varieties of mosquitoes are respon¬ 
sible for spreading both malaria and yellow fever. 

A comparison of the life-histories here outlined gives 
one a notion of the great variety of modifications of a 
common plan of structure to compass different objects. 
How these modifications have come about in the 
progress of insect-life is one of the most interesting 
problems before the student of nature’s ways. The 
change from a caterpillar with biting mouth-parts to a 
butterfly with his long proboscis gives a hint of the 
possibilities of evolutionary growth. 

Questions. 1. Have you observed closely the life- 
history of any insect ? If so, what are some of the 
changes you have noticed ? 


Fig. 77.—The Mouth of 
a Female Mosquito. 










A CHAPTER OF LIFE-HISTORIES. 85 

2. What advantages and what disadvantages must 
be experienced by a larva living in water ? 

Topics for Reports. The Life-history of a Beetle. 
A Life-history I have Observed. 


VOCABULARY. 


A phis, pi. aphides (Gr. apheides , 
lavish), a plant-louse. 

Cad'dis-fly, a name given to an in¬ 
sect whose larva lives in the 
water and builds for itself a 
tubular case. 

Gnat, a mosquito. 

Ich neu'mon (Gr. ichneuo , to hunt), 
a genus of insects belonging to 
the hymenoptera. 

Mi cro gas'ter (Gr. mikros , small, 
and gaster , stomach y a small 
hymenopterous fly. 


Mo squi'to (Lat. musca , a fly), a 
well-known dipterous insect. 

Par then 0 gen'e sis (Gr. parthe- 
nos , a virgin, and gignomai , to 
be born), reproduction by means 
of unfertilized eggs. 

Pro'leg, one of the fleshy abdom¬ 
inal legs of insect larvae. 

Pu pa'tion (Lat. pupa , a doll), the 
process of undergoing the pupal 
condition. 



CHAPTER VIII. 


SOME INSECT ADAPTATIONS. 



Structure and Habits. Fig. 78 shows the parts of 
the hinder leg of a cockroach, an 
insect whose legs are well adapted 
for running. Comparing this leg 
with the corresponding legs of a 
grasshopper, we find the same 
parts present but modified for 
jumping. Looking at the legs 
of a mole-cricket, we find again 
the same parts, but in this case 
altered for digging. Among the 
large water-bugs, which live by 
hunting, the legs are fitted for 
seizing and holding prey. In 
some of these bugs, a portion of 
the leg 
forms a 
sheath into 

which another portion shuts 
like the blade of a 
pocket-knife when 
not in use (Fig. 80). 

Aquatic insects 
like the water-boat- 
m a n (Notonecta) 
and the large water- 
beetle (Ditycus) 
have legs made into powerful oars, which they are 

86 



Fig. 78. —Leg of a Cock¬ 
roach. a , coxa; b , 
trochanter; c, femur; 
d , tibia; e, tarsus. 


Fig. 79.—A Mole-cricket. 



SOME INSECT ADAPTATIONS. 


87 


even able to feather as they row along, yet here, as 
elsewhere, the plan of structure is the same as that 



Fig. 80.—Fore Legs of a Water-bug. B , open; A , closed; C, enlarged 
• to show sheath. 

seen in the cockroach and grasshopper. Some butter¬ 
flies of strong flight use their legs so little that their 
front legs are mere threads, yet they retain the marks 




Fig. 81.—Legs of Dyticus. A , hind legs for swimming; B , fore leg 
with suckers. 


of the same plan we have found in the other insects 
examined. 

What is true of the legs is also true of other impor- 



88 


ANIMAL ACTIVITIES, 


tant organs. Devices for defence, for eluding enemies, 
and for procuring appropriate food among insects are 
everywhere seen to be varied modifi¬ 
cations of the same organ or organs. 
In general such structures are found 
in any particular insect as best help 
it to preserve its life in the particular 
Fig. 82.—Fore Leg environment in which it lives. So 
of a Butterfly. much does the structure tell us about 
the mode of life, that we are often 
able to infer the habits of an insect which we have 
never seen alive from the study of dead specimens, and 
even from fossil remains. 

Changes of Organs Because of Changes of Habit. 

That these variations of similar organs have arisen 
gradually, through changes of habit made necessary 
by changes in surroundings, is generally believed. 
At first sight the long delicate proboscis of the butter¬ 
fly, the lapping tongue of the house-fly, the beak of 
the aphis, the hard, biting jaws of the beetle seem very 
different structures, but when we watch the caterpillar 
of the butterfly and the grub of the beetle with mouth- 
parts so much alike at the start, and see that in one 
case the maxillae elongate into the coiled proboscis, 
and in the other the mouth-parts grow into the formid¬ 
able and destructive biting-organs of a carnivorous 
beetle, we wonder less at the divergence than at the 
resemblance. We see, too, how it may have been 
possible for organs very unlike to have arisen from 
similar beginnings. The great variety seen in the 
breathing-organs of aquatic insects furnishes another 
illustration of the change of organs necessitated by a 
change of habit. From the fact that all aquatic insects 
breathe air by tracheae at some period of their life it is 
believed that their ancestors, as well as the ancestors 
of insects having aquatic larvae, were originally terres¬ 
trial. Either driven by enemies or lured by more 
abundant food, at some distant period, these insects 



SOME INSECT ADAPTATIONS. 


89 


began an aquatic life to which they became gradually 
adapted by a process similar to that by which the 
butterfly obtains his protective coloring. In fact the 
aquatic life is a protection, either from destructive 
enemies or from starvation. 

Insect Communities. In speaking of the life-history 
of the aphides we mentioned the fact that ants some¬ 
times keep these insects to provide them with honey- 
dew. It is also true that some ants capture the pupae 
of ants of other communities than their own and rear 
them as slaves. To obtain these pupae wars are often 
waged, hence cooperation is necessary. Cooperation 
leads to life in communities and life in communities 
makes necessary a division of labor, so that we find 
nurses, foragers, soldiers, queens, and drones working 
together in the same community, all developed from 
eggs which are apparently just alike. 

This production of seemingly different insects seems 
to be sometimes a matter of choice on the part of the 
rulers of the community, for it has been found that a 
worker grub, among bees, may be developed into a 
queen by the use of special food and the building of a 
royal chamber. This division of labor is best illustrated 
among bees, ants, and wasps. 

Hive-bees. In a bee community there is one female 
called the queen who produces all the eggs. There 
are a small number of males called drones. All the 
rest of the inmates of the hive are workers. The 
workers are in reality immature females. They are 
provided with stings which are modified ovipositors. 
The wax is produced within the bodies of these workers 
and issues from between the segments of the abdomen, 
whence it is taken and skilfully built into the honey¬ 
comb, with which all are familiar. The honey, when 
taken from the nectaries of flowers, passes into a sort 
of crop, or honey-bag, where it undergoes changes 
which alter its flavor. It is then brought to the hive 
and stored in the cells of the honeycomb. The young 


9 o 


ANIMAL ACTIVITIES. 


bees hatch from the egg as larvae, or maggots, in cells 
much like the honey-cells. In these cells they find a 
bountiful supply of food, known as bee-bread, which 
is composed of honey and pollen gathered by the 
workers. In these cells, too, 
the young bees pass through the 
stages of complete metamorpho¬ 
sis. 

Insects and Plants. Besides 
the adaptations which fit insects 
to cooperate with one another, 
there are also equally wonderful 
adaptations of structure fitting in¬ 
sects to cooperate with plants to 
their mutual advantage. It is 
well known that plant-seeds, as 
well as the fertile eggs of animals, 
are produced only by the union of 
two kinds of cells, the male ele¬ 
ment being called the fertilizing 
cell. Among plants, pollen-cells 
grown on the stamens of flowers 
must fall upon the stigma and be 
conveyed thence to the ovary 
before seeds suitable for repro¬ 
duction can be formed. In many 
cases the pollen from one flower 
must be conveyed to the stigma 
of another flower before fertiliza¬ 
tion can take place. This carry¬ 
ing of pollen from flower to flower 
is the work of insects which visit 
the flowers for the purpose of getting honey. On the 
visit, the pollen adheres to the hairs or other parts of 
the insect’s body, and is rubbed off by the stigma of 
the next flower approached. 

Each flower seems to depend on a particular insect 
whose proboscis just fits its own honey-cup. Thus, 



Fig. 83.—Hive-bees. 1 
female; 2, male; 3 
worker. 


SOME INSECT ADAPTATIONS. 


9 1 


red clover cannot grow without the help of bumblebees. 
No more can bumblebees flourish without the honey 
prepared by the growing clover. When this partner- 




Fig. 84.—Fertilization of a Flower by an Insect. ar, calyx; b, curved 
upper lip; c, under lip, on which the bee stands while sucking the 
honey; d, pistil; d ', pistil at a later stage; e , stamen; <?', stamen 
shedding the pollen from its anther on the back of the bee; f } bee’s 
proboscis, with which it reaches the honey. 


ship between the bee and the clover began we cannot 
say, but there is reason to believe that passing years, 
with their new generations of both bees and clover, 
only increase the dependence of each upon the other. 





9 2 


ANIMAL ACTIVITIES. 


If you examine a head of the common white clover, 
so abundant everywhere, you will see a part of the tiny 
flowers of which the head is composed standing erecl 
and looking their best and prettiest. These are the 
flowers not yet visited by the bees; the dry and 
withered flowers hanging down near the stem have 
been fertilized, and each one now contains a pod in 
which the tiny clover-seeds are ripening. 

Not only do we find the proboscis of an insect fitted 
in structure for the plant on which it habitually feeds, 
but we find the plants, also, ordering their ways to 
conform to the habits of their insect friends. Thus, 
stamens grow in such a way that they must dust 
their pollen on the insect as he reaches the honey-cup, 
while stigmas reach out in their growth to occupy at 
maturity a position in the pathway of the pollen-laden 
insect. Not only do stamens and stigmas seek the 
insect, but the petals call their friends by color-signs 
and point out by brilliant lines the direction of the 
honey-cup, while hostile barbs and pointed hairs below 
the cell of nectar prevent the approach of honey-loving 
ants and small insects not useful to the plant. 

Questions. What structures would lead you to sus¬ 
pect that an insect leads an aerial life ? an aquatic life ? 
a terrestrial life ? 

Knowing an insect to be capable of strong flight, 
what might you reasonably predict concerning this 
insect’s legs ? 

What might the mouth-parts of an insect indicate 
concerning its food ? 

What adaptations have you noticed in insects you 
have observed ? 

In what ways have you known insects to be espe¬ 
cially protected from enemies ? 

Why do some insects commonly fly at night ? 

What insects have you observed at work at night ? 

What insect communities have you observed ? 

Have you seen insects carrying pollen ? 


CHAPTER IX. 


A SPIDER’S ACTIVITIES. 

PLACE a living spider in a large glass jar and watch 
its movements for several days. Get a garden-spider 
if possible, and keep it well supplied with flies and 
other insects. 

How does it take its food ? 

From what part of its body does its web issue ? 

Do all spiders make the same kind of web ? 

Where have you seen spiders ? 

Where have you seen the eggs of spiders ? How do 
they look ? 

Have you seen cast-off skins tangled in spiders’ 
webs ? If so does that indicate anything about the 
spider’s mode of growth ? 

Can the spider smell ? Test this point by bringing 
near the insect first a clean glass rod and then a rod 
dipped in a liquid having a strong odor. 

Can the spider see ? How far from her body can 
she see ? 

Using an alcoholic specimen, write resemblances and 
differences for spider and grasshopper. 

How many divisions of the body ? 

Simple or compound eyes ? How many ? 

How many legs ? 

How many segments in each leg ? 

Examine the feet with a microscope. 

At the end of the mandibles find the poison-fangs. 

Where are the spinnerets ? How many do you find ? 

93 


94 


ANIMAL ACTIVITIES. 


Under the abdomen near the cephalothorax find two 
openings to the air-sacs or rudimentary lungs. 

Summary of Drawings, (a) A spider seen from 
above X 3- 

(i b ) A front view of the mandibles X 5 - 

(^) A view of the top of the head showing the ocelli. 

(d) A hind foot much enlarged. 

The Spider’s Activities. We have already con¬ 
sidered the activities of the grasshopper, classifying 


these under six heads. We 
have spoken of these six 
kinds of activities as the .six 
functions of living things. 
In the spider these activities 
are carried on by the aid of 
finely adjusted machinery 
which we can only describe 
somewhat roughly here. 



F IG . 85.—A Spider’s Leg. which we can only describe 


Taking Food. The devices by which spiders of 
different kinds procure their food are well worthy of 
study. Nearly all spiders are aided in this work by 
silken threads spun from their own bodies. In the 
lower part of the spider’s abdomen there is a bag in 
which is secreted a glue-like substance which issues 
from the spider’s body at will, and hardens on exposure 
to the air. The wart-like projections on the lower side 
of the abdomen near its posterior end are pierced with 
many hundreds of minute holes, through each of which 
proceeds a microscopic thread of the glue-like fluid we 
have mentioned. The wart-like projections are called 
spinnerets. The hundreds of tiny threads from the 
spinnerets are grasped by the spider’s claws and twisted 
into several strands, which, woven together, make the 
fibre of which webs are built. A spider’s thread, then, 
is a rope of several strands, and each strand is com¬ 
posed of many hundred lines, yet it is so light that it 
floats in the air, so strong that it easily holds up many 
times the spider’s weight, so elastic that it does not 




A SPIDER’S ACTIVITIES. 


95 


break easily, but stretches when struck heavily by large 
insects, and so pliable that it can be moved into any 
shape. No wonder, then, that the spider values so 
highly her magic thread, and economizes it to such an 
extent that she even eats the broken webs rather than 
have them wasted. 

The spider’s web is used in different ways by different 
members of the spider family. The trap-door spider 
builds her cylindrical home underground, lining it with 
the most delicate silk, and fitting it with a hinged cover 
which she closes in time of danger, holding it firmly 
shut with her claws. 

The water-spider builds her dome-shaped home 
under water, arranging it like a diving-bell, and carry¬ 
ing to it bubbles of air from the surface (Fig. 86). 
Some spiders weave irregular, sprawling tangles of web 
to trap their prey, while others build in accordance 
with a methodical pattern. One spider spins her web 
in such a way that it entangles in its meshes particles 
of warm air, thus forming a balloon with which to float 
in the air. The wheel-shaped web of the common 
garden-spider is a marvel of skill. To make it the 
spider first spins a thread where the wind can waft it 
to an anchorage on some distant twig, or other support. 
This line she hauls taut with her claws, and then, 
dropping and swinging, always holding a thread, she 
makes the somewhat irregular outside framework for 
her more accurate geometrical web. She then puts in 
the spokes with great care, and beginning at the 
middle, winds a spiral thread to the circumference, and 
another back to the centre. The second spiral thread 
is covered with little, sticky, transparent bead.s stand¬ 
ing side by side, ready to catch the luckless fly by 
wing, or leg, and hold him fast. A touch of the finger 
to such a thread shows the adhesive quality of the 
beads, and a look at them under the microscope reveals 
their beauty. 

Such a web is not a nest, or a house; it is a trap. 


9 6 


ANIMAL ACTIVITIES. 


Commonly the spider builds her home at one side of 
the trap, and, holding in one claw a thread which she 



Fig. 86 .—Water-spider and Nest. 


has connected with the trap, she awaits the vibration 
which warns her that an insect is ready to be eaten. 
If the pull on the line indicates a fly, she simply goes 













A SPIDER'S ACTIVITIES. 


97 


directly to it, holds it in her mandibles, sucks the fluids 
from its body and throws away the shell. If, however, 
the pulling indicates a wasp or bee the movements are 
of a different kind. Then the spider shows both 
caution and alertness. If the insect is evidently too 
large to attack, the spider snaps a few threads of her 
web and sets the captive free with as little loss of the 
precious web as possible. If, however, there is a 
chance of victory, the spider spins more threads and 
winds them round and round her victim, until she has 
him so hopelessly entangled that she can safely kill 
and eat him at her leisure. 

The entrance to the spider’s mouth is guarded by a 
pair of mandibles with sharp fangs at their tips. These 
tips have holes near the ends, which lead by tubes to 
a poison-bag in the head. From these fangs the 
poison is squeezed into the body of the fly or other 
insect. 

Nutrition. The spider’s food is always liquid, and 
is pumped up into her stomach in somewhat the same 
way as the butterfly’s honey. In the stomach it 
receives fluids which change it chemically, so that it 
can be used to nourish the body. 

Respiration. Like the insects we have studied, the 
spider has spiracles for breathing, but so active and 
energetic an animal requires more oxygen than this 
arrangement seems able to give, and so it is provided 
with rudimentary lungs or air-sacs. These sacs are 
situated in the anterior part of the abdomen near its 
junction with the cephalothorax, and open by two 
minute holes just behind the last pair of legs. The 
chemistry of breathing is the same in all animals. 

Reproduction. The spider deposits her eggs in a 
cocoon of silk which she makes with great care, 
shaping it with her body as a bird shapes her nest. 
This cocoon, with its eggs, is fastened in a sheltered 
place. The young spiders are hatched quite complete, 
like their mothers, and begin at once to spin each a 


9 8 


ANIMAL ACTIVITIES. 


tiny thread. They moult often, and very soon, with¬ 
out any teaching, they know how to spin their tiny 
wheel-shaped webs. They eat other insects, as do 
their elders, and often dine on one another. For them 
the struggle for existence is a fierce one, and domestic 
relations count for little, the mother eating not only 
her own children, but often making a meal of her 
husband. In the spider family the mother is supreme 
and husbands and children fare but ill. 

Discovery. An examination shows how large is 
the nerve-mass concealed in the cephalothorax of the 
spider. Several ganglia have grown together and 
produced a sort of second brain, considerably larger 
than the nerve-mass which lies above the throat. 
Not only is this brain large, but as it is made by the 
concentration of many smaller nerve-masses, or gan¬ 
glia, it represents a great concentration of power. 
These nerve-masses are connected with the outside of 
the spider’s body everywhere by nerves, which carry 
to the central organs notice of all vibrations from with¬ 
out. The spider then is extremely sensitive to any 
change in its surroundings. It sees, though not very 
clearly, by means of eight eyes placed on the front part 
of the cephalothorax; it hears, if at all, by the vibration 
of the hairs on its body. It tastes and smells, we have 
no doubt; but its keenest sense is that of touch. 

Movements. The spider is capable of few move¬ 
ments and performs these exceedingly well. What 
she loses by the absence of wings she gains by increase 
of power and skill in the use of her legs. The making 
of a web often requires the most delicate movement 
and the greatest precision; and the spider shows this 
delicacy and precision to perfection. The wonderful 
thing about the spider’s automatic movements is the 
accuracy with which they are controlled. 

The Lithobius. For purpose of comparison a little 
time may be devoted to the many-legged brown insects 
which disappear so hurriedly when one overturns a 


A SPIDER’S ACTIVITIES. 


9b 


board or stone, in almost any field or garden. In 
some localities these animals are called “earwigs ”, in 
other places they are known as centipedes. Another 
name for the most common species is lithobius. Speci¬ 
mens may be easily obtained by using tweezers or a 
piece of cloth. They may be kept in alcohol or 
formalin. 

In note-books answer these questions: 

What is the habitat of this animal ? 

Does it prefer light or darkness ? 

Does it prefer moist or dry places ? 

Does it bite or suck its food ? 

In what respects does it resemble the spider ? The 
grasshopper ? 

How does it differ from both spider and grasshopper ? 

Does the number of segments correspond with the 
number of legs ? 

The front feet have poison-claws. Do these feet 
have the same shape as the others ? 

Drawing. A sketch of lithobius. 

Questions. i. How do the breathing-organs of a 
spider differ from those of the insects previously 
studied ? 

2. Do you think the spider’s breathing has any rela¬ 
tion to his activity ? 

3. Have you noted any protective devices among 
spiders ? 

Topics for Reports. The Cochineal Insect. 
Aphides. Shellac. The Silk-worm. The Manufac¬ 
ture of Silk Goods. The Caddis-fly. May-flies. The 
Ant-lion. The Noises of Crickets, Mosquitoes, and 
Bees. The Habits of Honey-bees. The Carpenter- 
bee. Agricultural Ants. Mud-wasps. How Flies 
Walk on Ceilings. The Senses of a Fly (experiments). 
The Senses of a Spider (experiments). Spider¬ 
webs. Water-spiders. Trap-door Spiders. Scorpions. 
Cheese-mites. Centipedes. Thousand-legs. Stings 
and Poisons. The Sense of Sight in Spiders. Where 



IOO 


ANIMAL ACTIVITIES . 


I Have Found Spiders. Are Spiders of Any Use ? 
The Mosquito’s Boat. My Experience in Rearing 
Butterflies. Lightning-bugs. Injurious Insects. Some 
Insect Friends. Aphides as Cows of Ants. Valuable 
Substances Furnished by Insects. The First Paper- 
makers. Do Insects Talk ? Insects I Dislike. 


VOCABULARY. 


A e'ri al (Gr. aer, the air), inhabit¬ 
ing the air. 

A quat'ic (Lat. aqua, water), in¬ 
habiting the water. 

Ceph al o tho'rax (Gr. kephale, 
head, and thorax ), the union of 
head and thorax in one division 
of the body. 

Drone, a male bee. 

Fau'na (Lat. Fauna , the sister of 
Faunus, the god of agriculture), 
the characteristic animals of 
a district. 

Habitat (Lat. habito , to dwell), 


the natural abode of an ani¬ 
mal. 

Ma rine' (Lat. mare , the sea), in¬ 
habiting the salt water. 

Range, the region in which an 
animal naturally lives. 

Spin ner et', one of the projections 
from which the spider’s web 
issues. 

Su ture (Lat. suo , to sew), a seam 
or joint. 

Ter res'tri al (Lat. terra , the earth), 
inhabiting or living on the land. 



CHAPTER X. 


HOMOLOGIES AMONG CRUSTACEA. 

LIVING crayfish can be bought in the markets of 
large cities. One or two of these should be kept in an 
aquarium with several inches of water in a place where 
the class may study their structure and their move- 



Fig. 87.—Side View of Crayfish, an, antenna; r, rostrum; cep, cephalic 
portion; tho, thoracic portion of cephalothorax; ab, abdomen. 

ments before attempting the laboratory exercise on the 
shrimp. 

Feed the crayfish with pieces of meat or fish, and 
note the manner of seizing and eating food. 

Touch the antennae with various substances. See 
“Outline for Requirements in Zoology ” printed by 
Harvard University. 

Notice how the crayfish walks and how it swims 
backward when disturbed. 


IOI 



102 


ANIMAL ACTIVITIES. 


Place some colored liquid from a pipette just in front 
of the thorax at the opening of the gill-cavity. 

For individual work by the pupil, the use of the 
shrimp is suggested because of the small expense and 
because of the necessary comparisons with the crayfish. 
Compare also with a lobster. The questions may be 
used with crayfish, shrimp, or lobster. 

Place the shrimp, crayfish, or lobster in a saucer 
with the head turned from you. 



Fig. 88 .—Dorsal View of Crayfish. 


In what ways does the shrimp resemble the grass¬ 
hopper ? 

How does it differ ? 

In what respects does it resemble a spider ? 

How does the exo-skeleton compare with that of the 
insects ? 

How many segments do you find in the abdomen ? 

Can you find any indications of a division between 
head and thorax ? 



HOMOLOGIES AMONG CRUSTACEA. 103 

Are there any evidences of segmentation on the 
under side of the thorax ? 

The appendages attached to the abdomen are called 
swimmerets. At the end of the abdomen is the telson , 
which forms with the last pair of swimmerets the tail 
of the shrimp. The large claws used for grasping prey 



Fig. 89. —Ventral View of Crayfish. 


are the first pair of legs. Count the legs and swim¬ 
merets. In what ways do the swimmerets differ from 
the legs ? 

Are all the legs alike ? What differences do you 
observe ? 

In front of the legs are three pairs of foot-jaws used 
for passing food from the large claws to the mouth. 
These are called maxillipedes. In front of the maxilli- 
pedes are two pairs of maxillae. In front of the maxillae 
are the mandibles. 

How many pairs of antennae do you find ? Are they 
branched ? 

How do the eyes differ from those of a grasshopper ? 






io4 


ANIMAL ACTIVITIES. 



Fig. 90. — Fourth Ab¬ 
dominal Segment of 
Crayfish. /, tergum; 
st , sternum; //, pleu- 
rum; /r, protopodite; 
en, endopodite; ex , ex- 
opodite. One append¬ 
age has been removed. 


Notice the form of one of the swimmerets on the 
second or third abdominal segments and compare all 
the swimmerets with this. 

How do the other swimmerets 
differ from the ones first exam¬ 
ined ? 

Infer a use for the sixth pair of 
swimmerets. 

Sketch a swimmeret, naming 
parts. 

Compare the ends of the legs 
having pincers with those which 
do not have those organs. How 
much extra growth would be 
needed to produce a pair of 
pincers on the last pair of legs ? 

Examine all the jointed ap¬ 
pendages on one side of the 
body. How many do you find ? Counting a pair of 
appendages to each segment or somite y how many 
segments has a crayfish or shrimp ? 

How do the mouth-parts of a crayfish or shrimp differ 
from those of a grasshopper ? 

Remove one side of the carapace and expose the 
gill-cavity. Do you find gills at the base of all the 
legs ? Do you see the spoon-shaped gill-scoop ? Of 
what appendage is it a part ? 

Look on the inside of the basal joints of the legs to 
find the outlets of the reproductive organs. Among 
crayfish the females have these openings on the middle 
pair of legs and the males on the last pair. 

With the help of the drawings find the openings of 
the green glands (renal openings). 

Find the ear. 

Where is the anal opening ? 

Internal Structure. With an alcoholic specimen 
one can make out the parts indicated in the figure 
below. The position of the heart, digestive tube, and 


HOMOLOGIES AMONG CRUSTACEA . 


105 


nervous system should be especially noted. In looking 
for the heart remove the top of the carapace where you 
see the depression just behind the line between head 
and thorax. 

Summary of Drawings. ( a ) Side view of shrimp 
X 4 (omitting appendages). 



Fig. 91. Crayfish Appendages. A , antennule; B , antenna; C, man¬ 
dible; D, second maxilla; E , second maxillipede. 


( b ) The carapace seen from above X 4- 

(c) Side view of thorax with carapace removed to 
show gills X 4* 

(d) An eye seen from above X 6. 

(e) Large antenna X 6. 

(/) Small antenna X 6. 

(£•) First, second, and last leg X 4* 







io6 


ANIMAL ACTIVITIES. 


(//) A swimmeret from the third abdominal segment 
seen from behind X 6. 


(z) Sixth swimmeret. 

Homologies. In the lobster, shrimp, and crayfish, 
the antennae, claws, legs, and swimmerets are seen to 



be similarly situated and to bear a strong resemblance 
in structure. If we should study the growth of these 
three animals, we should find that these appendages 
arise in a similar way in the process of development. 
Parts of animals similar in position, structure, and origin 
are said to be homologous. The wings of the butterfly 
are homologous with those of the grasshopper. The 
three pairs of jointed legs in the caterpillar are homol¬ 
ogous with the legs of the butterfly. 

When parts correspond simply in use and not in 
origin or structure, they are said to be analogoits. 
Thus the. wing of a bird and the wing of a butterfly are 
analogous but not homologous. 





HOMOLOGIES AMONG CRUSTACEA. 107 

Serial Homology. In comparing the jointed appen¬ 
dages of the different segments of the abdomen of a 
lobster or crayfish with one another, 
we note the fact that each is com¬ 
posed of a basal joint of two seg¬ 
ments and a pair of jointed branches. 

One part of the basal joint is called 
the basipodite and the other the cox- 
opodite; both together are called the 
protopodite. The inner branch is 
the endopodite, and the outer branch 
the exopodite. In the other jointed 
appendages we find striking similarity 
to the swimmerets. They are also 
similar in origin; starting as bud-like 
outgrowths from the rings or somites 
of the embryo. Indeed, each seg¬ 
ment is homologous with every 
other. This kind of homology is 
called serial homology. It is very 
noticeable among the Crustacea. 

Laboratory Exercise. Examine Fig - 93—Walking 

, , , Appendage o f 

a sand-hopper and an asellus. Crayfish with Gill, 

How does each compare with the g , Attached, 

shrimp in regard to: 

(a) The number of legs ? 

(1 b ) The number and form of swimmerets ? 

( c ) The number of antennse ? 

(d) The number of segments ? 

(^) The divisions of the body ? 

(/) The eyes ? 

(g-) The carapace ? 

(/i) The position of the gills ? 

(z) The general form of the body ? 

Name parts of the sand-hopper which are homol¬ 
ogous with those in the shrimp. 

Name an organ in the sand-hopper which is anal¬ 
ogous to one in the shrimp but not homologous with it. 



io8 


ANIMAL ACTIVITIES. 


Compare the eyes in the three animals. 

The Importance of Homologies. We have already 
pointed out the fact that parts may be homologous and 



Fig. 94. —The Common Crab. 

yet appear very unlike. Parts which arise in the same 
way in the processes of development may become so 



Fig. 95.—Early Stages of Shore-crab. 


variously modified that their real homologies could not 
be known without a study of embryology. Hence it 






HOMOLOGIES AMONG CRUSTACEA . 


109 


frequently happens that animals bearing only slight 
external resemblance to one another in adult life are 
classified together because 
in embryological life they 
show so many resem¬ 
blances. 

Among the ten thou¬ 
sand or more species of 
Crustacea, there are many 
strange forms which de¬ 
part from what might be 
called the typical crusta¬ 
cean structure. Compar¬ 
ing the common crab 
(Cancer irroratus) with the 
shrimp or crayfish, we 
notice the small size of 
the abdomen folded under 
the flattened carapace. In 
the hermit crab the abdo¬ 
men is soft and has lost part of the swimmerets, be¬ 
cause of its habit of using the shell of a snail for pro¬ 
tection, yet in the young the abdomen of this animal 



Fig. 


96. — Water-flea (Daphnia 
pulex). 



Fig. 97.—Cyclops. A, dorsal view; B , side view. 


is essentially like that of the young crayfish and bears 
homologous parts. 


IIO 


ANIMAL ACTIVITIES. 


Among the lower Crustacea there are many which 
show greater variations from the typical form. The 
cyclops is a small lobster-like crustacean often found 
in drinking-water. Specimens can usually be obtained 
by tying a piece of muslin over the end of a faucet and 
allowing the water to run for a little while and then 
rinsing the muslin in a glass of water. The horseshoe 
crab is an ancient form sometimes classified with the 
spiders because it seems to have more homologies with 
them than with the common forms of Crustacea. 

Degeneration. The lower Crustacea are called Ento- 
mostraca. Among these are found many forms which 

would not be recog¬ 
nized as allies of the 
crayfish and crab, but 
for the study of their 
embryology. The 
common barnacle 
(Balanus) found on 
all salt-water shores 
between high and 
low tide bears no re¬ 
semblance to a cray¬ 
fish, yet soon after 
hatching from the 
egg it is a free- 
swimming active crustacean, provided with organs of 
sense and looking much like a young shrimp. After 
a short time it seems to tire of its active life, and, 
looking about for a place of rest, it glues its head to a 
rock and lies feet uppermost kicking food into its mouth 
from the surrounding water. It builds around itself a 
conical shell which it opens and closes at pleasure. 
Thus sitting at ease and catching food as it comes, it 
has no use for organs of sense or locomotion and so 
loses these marks of higher animal life. It finally 
becomes a blind and stupid mass, capable of little 
else than the digestion of food brought to it by the 



Fig. 98.— A Barnacle. 



HOMOLOGIES AMONG CRUSTACEA. 


in 


waves, an excellent illustration of the loss of powers 
by disuse. 

There are also many forms of fish-lice which live a 
parasitic life by attaching themselves to a portion of 
some fish and living on either the blood or food of their 
host. These bear very little resemblance to the cray¬ 
fish. Some have even lost the gills and breathe only 
by the external surface of the body. These fish-lice 
hatch from the egg as free-swimming larvae, bearing 
a striking similarity to other Crustacea at this stage 
of growth. The common larval form is called the 
nauplius . (See first stage in Fig. 95.) It has a single 
eye and three pairs of appendages. The higher Crus¬ 
tacea pass through this nauplius stage before hatching 
from the egg. From this stage, the higher forms of 
Crustacea which lead an active life develop more ap¬ 
pendages, and more acute sensibilities, with a corre¬ 
sponding increase of complexity in the nervous system, 
while the parasitic forms lose the eyes and locomotive 
appendages, and their whole structure degenerates into 
machinery for digestion and reproduction. 

AN EXERCISE FOR THE NOTE-BOOK. 

Rule a page in your note-book in the manner indi¬ 
cated on p. 112 and fill the blank spaces with such 
descriptive terms as you have learned in the previous 
lessons. 

Classification of the Arthropoda. We have already 
noted the characteristics of the class “ Insecta ” by 
selecting the points of resemblance among them. We 
readily see that the spider, the lithobius, and the cray¬ 
fish cannot be classed as Insecta without changing our 
present definition. We find it more convenient to 
include all the animals thus far studied in a larger class 
which naturalists have agreed to call Arthropoda. 
The Arthropoda are called a sub-kingdom or phylum 
because they constitute one of the large divisions of the 


112 


ANIMAL ACTIVITIES . 



Grass¬ 

hopper. 

Spider. 

Lithobius. 

Shrimp. 


Bilateral ? 






Are appendages 
jointed ? 






Wings, antennse, 
legs, and swini- 
merets. 






Divisions of 
body. 






Respiration. 






Locomotion. 







animal kingdom. Sub-kingdoms are divided into 
Classes, classes into Orders, orders into Families, 
families into Genera, genera into Species. Thus the 
milkweed-butterfly belongs to the sub-kingdom Ar- 
thropoda, the class Insecta, the order Lepidoptera, the 
family Nymphalidae, the genus Danais, and the species 
Archippus. Such an arrangement must be to some 
extent artificial, because animals are not run in molds 
like bullets or stamped with dies like coins. Never¬ 
theless, the great number of animal forms compels us 
to adopt some scheme of classification to prevent con¬ 
fusion. 

Examining our notes concerning the Arthropoda, 
we find that all are bilateral, all have an exoskeleton, 
segmented bodies, and jointed appendages. These 





























HOMOLOGIES AMONG CRUSTACEA. 113 

peculiarities we may call the most important character¬ 
istics of the Arthropoda. Animals not having- these 
marks must be classified under other sub-kingdoms. 
In Chapter I we have classified all animals into eight 
sub-kingdoms. The sub-kingdom Arthropoda includes 
probably half of the animals of the earth, the Insecta 
alone having more than half a million species. Nat¬ 
uralists are not agreed yet as to the number of classes 
properly belonging to the Arthropoda, but usually 
animals like the shrimp and crayfish are called Crus¬ 
tacea, those like the lithobius Myriapoda, those like 
the spider Arachnida, and those like the grasshopper 
Insecta. The Insects have already been described. 

The Arachnida have eight legs, simple eyes, and a 
cephalothorax and abdomen. 

The Myriapoda have many segments with at least 
one pair of jointed legs for each segment. 

The Crustacea breathe by gills throughout life. 
They pass through the nauplius stage in the course of 
development. 

Further study shows other marks for identifying 
these classes. Many exceptional forms are found and 
great patience and care are necessary in order to 
classify accurately. Nevertheless, it is profitable prac¬ 
tice to attempt to classify animals as we see them, even 
if we do it somewhat roughly at first. 

Laboratory Exercise for Review. A variety of 
forms kept separately in small numbered boxes and 
bottles may be used. Write in the note-book: 

(1) The number of the specimen. 

(2) Its mode of locomotion. 

(3) Its habitat, inferred from its structure and its 
resemblance to forms already known, with the reason 
for your answer. 

(4) Its food and its mode of procuring it, inferred 
from an examination of its mouth-parts, from other 
points of structure, and from resemblances to forms 
already known, with the reason for your answer, 


ANIMAL ACTIVITIES. 


114 

(5) The class to which it belongs, with reasons for 
the answer. 

(6) In the case of Insecta, name the order to which 
the insect belongs, with reasons for the answer. 

Questions. (1) Why are the animals just studied 
called Crustacea ? 

(2) How does their manner of breathing compare 
with that of Insecta ? 

(3) Do lobsters breathe air ? Explain. 

(4) What is meant by homology ? By analogy ? 

(5) What is serial homology ? 

(6) Where may one find cyclops ? 

(7) Why is cyclops so named ? 

(8) How do the crabs differ from the shrimp ? 

(9) In what way do barnacles resemble the shrimp ? 

(10) How does the hermit-crab differ from other 
crabs ? 

(11) In what cases among Crustacea does the mode 
of life seem to affect the shape of the body ? 

(12) What occurs when the limb of a crustacean is 
broken off ? What reason have you for your answer ? 

(13) What is phosphorescence? How do you ex¬ 
plain it ? 

(14) Do the Crustacea moult ? How do you know ? 

(15) Do you know any animals which do not have 
both sides alike ? 

(16) Give examples of differentiation. 

Topics for Reports. The Hermit-crab. Robber- 
crabs. Lobsters. Cyclops. Phosphorescence. Giant 
Crustacea. Degeneration. Uses of Crustacea. 


HOMOLOGIES AMONG CRUSTACEA. 


Ir 5 


VOCABULARY. 


An al'o gous (Gr. ana, according 
to, and logos .) Analogous organs 
are those having the same use 
but not necessarily the same 
structure or origin. 

Bas ip'o dite (Lat. basis, base, and 
Gr. poas , foot), part of a crus¬ 
tacean appendage. 

Car'a pace (Lat. capara, a hood), 
the hard covering of the cephalo- 
thorax in Crustacea. 

Ceph al i za'tion (Gr. kephale, 

head), a tendency to aggregate 
nerves and organs of sense near 
the head. 

Cox op'o dite (Lat. coxa , hip, and 
Gr. pous), the joint of a crusta¬ 
cean appendage nearest the body. 

Crus ta'ce a, a class of arthropoda 
commonly having a hard shell. 

Dec a pod(Gr. deka , ten, and pous), 
an order of Crustacea having ten 
legs. 

Dif fer en ti a'tion (Lat. dis , apart, 
and fero , to carry), the setting 
apart of tissues and organs to 
perform special kinds of work. 

Em bry ol'o gy (Gr. embryon , an 
embryo, and logos), the study of 
embryonic life. 

En dop'o dite (Gr. en, in, and pous), 
the outer branch of a swim- 
meret. 

Ex u'vi um (Lat. exuo , to strip off), 
the cast-off skin of an insect or 
crustacean. 

Fang, a hollow tooth emitting 
poison. 

Fer til i za'tion (Lat .fero, to bear), 
the union of male and female 
cells to produce living seeds or 
eggs. 


Gill, an organ for breathing the 
oxygen dissolved in water. 

Ho mol'o gous (Gr. homos, same, 
and logos), having the same rel¬ 
ative position and structure. 

I'so pod (Gr. isos, equal, and pous), 
an order of Crustacea having the 
legs of equal length. 

Max il'li ped ( maxilla, and pous), 
a foot-jaw. 

Os mo'sis (Gr. osmose, pushing), 
an interchange of gases or 
liquids through a slightly porous 
substance. 

Pro top'o dite (Gr. protos, first, 
and pous), a part of a swimmeret 
consisting of the basipodite and 
coxopodite. 

Re'nal (Lat. renalis, kidney), per¬ 
taining to the kidneys. 

Ros'trum (Lat. rostrum, a beak), 
a weapon of defence on the front 
of the carapace of a crustacean. 

Sed'en ta ry (Lat. sedeo, to sit), 
inactive. 

Ses'sile (Lat. sedeo, to sit), joint¬ 
ed to the body without stems or 
stalks. 

So'mite (Gr. soma, a body), a 
segment of the body of one of 
the arthropoda. 

Swim mer et', a jointed appendage 
on the abdomen of a crustacean. 

Tac'tile (Lat. tango, to touch), 
having the sense of touch. 

Tel'son (Gr. telson, a boundary), 
the posterior somite of a crus¬ 
tacean. 

Tet ra dec'a pod (Gr. tetra, four, 
deka and pous), an order of 
Crustacea having fourteen legs. 




CHAPTER XI. 


THE ACTIVITIES OF ONE-CELLED ANIMALS AND 
SPONGES. 

THUS far we have been dealing with animals having 
more or less complicated machinery for carrying on the 
activities of life. We know that an egg is a single cell 
and that as it grows it changes by increasing the num¬ 
ber of cells and by setting apart groups of these cells 
to perform different duties. In a single cell life is 
reduced to its lowest terms. In an egg we may see 
the process of unfolding and get greater insight into 
the workings of living machinery. So in studying 
living animals which never develop beyond the single¬ 
cell stage of existence we may gain a knowledge of 
animal activities not otherwise obtainable. 

These animals are so small that a complete study of 
them makes necessary the use of the compound micro¬ 
scope, but as it is not proposed to burden this course 
with the details of microscopic manipulation, we must 
content ourselves with verbal descriptions for the 
present. 

The one-celled animals are put in a sub-kingdom by 
themselves, called Protozoa. They are very small and 
for the most part inhabit the water. There are many 
of them, but their ways may be very well understood 
by studying descriptions of a few forms. 

The Amoeba. This minute animal has been much 
studied and its modes of life are well known. It may 
be found in stagnant water in small shallow pools. It 
is less than a hundredth of an inch in diameter and 

116 


ONE-CELLED ANIMALS AND SPONGES. 117 

under the microscope looks like a drop of moving jelly 
of irregular outline. The greater part of the Amoeba 
is granular in structure, being surrounded by an outer 
film of clearer jelly. In the midst of the cell is a 
nucleus , a little more opaque than the rest of the cell 
but made of the same substance. The jelly-like sub¬ 
stance of which the whole Amoeba is made is called 



Fig. 99.—Forms of Amoebae (highly magnified). 2 and 3 were drawn 
from the same specimen; 5, 6, 7, and 8 were drawn from another 
specimen; A r , nucleus; P, pseudopodia. 

protoplasm. The same substance is found in the cells 
in our own bodies, as well as in the living cells of other 
animals and plants. Every plant and every animal 
begins its life as a single cell of protoplasm. Within 
the Amoeba’s cell may be also seen a round clear spot 
which from time to time contracts and temporarily dis¬ 
appears. This is called the contractile vacuole. 




118 


ANIMAL ACTIVITIES. 


Taking Food. Not only is the Amoeba destitute of 
jaws and sucking-tubes, but it even lacks a mouth. 
Its food consists largely of minute one-celled organisms 
which it swallows at any part of its body by simply 
flowing over and around them. 

Nutrition. The particles of food which have been 
swallowed are gradually dissolved and chemically 
changed so as to become a part of the protoplasm of 
the Amoeba’s body. The shell of the plant is thrust 
out through the Amoeba’s covering at any point when 
all the nutritious matter has been taken from it. Dis¬ 
solving and chemically changing the food is digestion. 
Making it a part of the Amoeba’s protoplasm is assimi¬ 
lation. There is no stomach or intestine, but the food 
while digesting moves about with the granular proto¬ 
plasm in a somewhat regular way. 

Respiration. There are no organs for breathing, 
but oxygen from the surrounding water enters the living 
protoplasm and carbon dioxide and other impurities 
are given off. 

Reproduction. When the Amoeba has eaten and 
digested food until it has grown to be too large, the 


nucleus shows signs of divid¬ 
ing, the Amoeba assumes a 
dumbbell shape and finally 
splits into two Amoebas, 
each equally capable of 



Fig. ioo.— Amoeba Feeding. leading an independent ex¬ 

istence. Parent and off¬ 
spring are alike, if either can be called parent. This 
mode of reproduction by division is called fission. 

Discovery. If touched the Amoeba contracts. It 
is then sensitive to touch, but there can be no special 
parts of the body fitted to receive impressions from 
without. It is everywhere equally sensitive. 

Movements. Not only does the Amoeba withdraw 
when touched, but it seems capable of self-directed 
movement as well. The method of procedure consists 


ONE-CELLED ANIMALS AND SPONGES. 119 

in projecting outward a portion of the body in the 
direction in which the animal wishes to move. The 
little swelling thus made is called a pseadopodiuni or 
false foot. Such false feet may appear at any time on 
any part of the body. When this pseudopodium has 
extended itself sufficiently the rest of the body seems 
to glide into it by a sort of flowing motion. The varying 
position and size of the pseudopodia give it its irregular 
outline when seen under the microscope. The Amoeba’s 
power of “contractility ” is sometimes spoken of as a 
separate activity corresponding to the contractility 
noticed in the muscles in higher animals. 

Thus this simple bit of protoplasm performs the same 
functions which are common to higher animals, all the 
activities in this case being carried on by a single cell. 
As we examine other animals we find it easy to arrange 
a series in which each animal is only a little more 
specialized than the one next below it, but such a series 
does not include all animals. It is interesting to note 
that such a series bears a strong resemblance to the 
various stages through which an egg (a single cell) of 
one of the more specialized members of the series 
passes in its growth. 

Rhizopoda with Shells. Some of the Amoeba-like 
animals cover their bodies with bits of mineral matter 
to form shells with openings 
through which the pseudopodia 
extend to gather food and as¬ 
sist in locomotion. In many 
cases these shells are secreted 
by the animal, that is, they are 
formed from the protoplasm 
of the body as our finger¬ 
nails are formed from our blood. Sometimes the 
pseudopodia resemble the roots of plants and hence 
these Protozoa which move by pseudopodia are called 
Rhizopoda. 

Some of the Rhizopoda secrete shells of calcium car- 



120 


ANIMAL ACTIVITIES . 


bonate or limestone. When these shells are perforated 
with many holes the animals are called Foraminifera. 



Fig. 102.— One of the Foraminifera. 


Some of these foraminifera have been found of large 
size and in such great numbers that their fossil remains 
make great deposits of limestone. 




A B 

Fig. 103.—The Origin of Chalk. A, chalk ( magnified ); B, ooze (mag- 
nijied). 


Chalk. At present there live near the surface of the 
ocean great numbers of these shelled Rhizopods. 




ONE- CELLED ANIMALS AND SPONGES. 


121 


When they die their shells fall to the bottom and, 
mingling there with other similar shells, form a soft 
white mud which may harden to form chalk. The 
chalk cliffs of England were doubtless produced in this 
way. 

Tripolite. Some of the Rhizopoda have shells made 
of the finest possible bits of glass or silica. Deposits 
of these shells with similar shells of one-celled plants 
form tripolite, a substance used as a polishing powder. 

Infusoria. If hay be placed in warm water and 
allowed to stand in a warm place for a few days the 



Fig. 104.—Infusorial Earth 

( magnified ). 


Fig. 105.—Infusorians 
( magnified ). 


water will be found to be filled with many minute, one- 
celled, rapidly moving animals. A look at these 
through the microscope shows that their movements 
are due to the motion of hair-like projections on the 
body. These hair-like bodies are called cilia . One- 
celled animals which move by cilia are called Infusoria 
because some of their kind appear when infusions of 
hay or other vegetable matter are allowed to stand. 
Some of the Infusoria are fixed by a stalk, or stem, like 
the bell-animalcule, or vorticella, shown in the figure, 
and some are rapidly moving free animals like those 
found in infusions of hay. 


122 


ANIMAL ACTIVITIES. 


One of the Infusoria found in infusions of vegetable 
matter is the Paramecium , or slipper-animalcule (Fig. 

107). This may be found and stud¬ 
ied very easily. Where a compound 
microscope is available the follow¬ 
ing exercise may be used. 

Laboratory Exercise. Examine 
in a watch-glass by using a low 
power of the microscope a few 
drops of stagnant water known to 
contain Infusoria. 

1. Does the Paramecium have a 
definite shape ? Is it bilateral ? Is 
the Amoeba bilateral ? 

2. Place a few drops of water 
containing the slipper-animalcule 
on a slide with a few fibres of cot¬ 
ton and examine with a higher 
power of the microscope. Is the 
body divided into parts or cells ? 

3. Do you see the movement of 
cilia ? On what part of the body 
are they situated ? 

4. Do you find a groove sur¬ 
rounded by cilia ? 

a mouth ? 
a nucleus ? 

Are there any contractile vacuoles ? 

Feed the animal with bits of indigo, 
the blue particles go ? 

Summary of Drawings. ( a ) A sketch of several 
animals as they appear when viewed with a low power 
of the microscope. 

( b ) Sketch of a single animal showing as many parts 
as you have seen. 

In the Paramecium the activities of life are carried 
on much as they are in the Amoeba. There is, how¬ 
ever, a greater specialization of parts, especially the 



Fig. 106.— Vorticella 
( magnified ). A , ex¬ 
tended ; 3, contract¬ 
ed; C, in fission. 


Do you find 
Do you find 


Where do 



ONE-CELLED ANIMALS AND SPONGES. 


123 


tfiouth for taking food and the two kinds of cilia, one 
for locomotion and one for producing currents of water 
to drive food into the 
mouth. Even a single 
cell then may have its 
parts specialized for per¬ 
forming different kinds of 
work. 

Characteristics of the 
Protozoa. The Protozoa 
are minute animals 
having but a single cell 
of protoplasm, moving by 
pseudopodia, or cilia, and 
reproducing withouteggs. 

Sponges. It is not rec¬ 
ommended that sponges 
be studied in the labora¬ 
tory in an elementary 
course, but for purposes 

a rnugrujicu j. v.g.y uic11 giuuvc j 

of comparison it is neces- ph, pharynx, 
sary to become familiar 

with the most important facts concerning their structure. 

Sponges are composed of many cells but slightly 
specialized. A single sponge really seems almost as 
much like a colony of Protozoa as like a distinct animal. 
The outer layer of cells which is simply a sort of skin 
is called the ectoderm; the inner layer or lining of the 
cavities of the body is called the endoderm. Between 
the ectoderm and the endoderm lies the mesogloea , in 
which the skeleton is produced. The flesh of the 
sponge taken altogether is called sarcode. The com¬ 
mon bath-sponge as we use it is only the skeleton. 
We may imagine that the hard parts we see have once 
been imbedded in fleshy matter (mesogloea); that the 
fleshy matter was covered with a skin (ectoderm); and 
that the cavities so apparent in the skeleton were lined 
with another skin (endoderm). 



124 


ANIMAL ACTIVITIES. 


The kind of sponge commonly called the hard-head 
gives a general idea of sponge-structure. The smaller 
holes on the outside correspond to openings in the 
ectoderm through which currents of water flow to the 
interior cavities. The large holes at the top are out- 



Fig. 108. —Structure of a Sponge ( magnified ). A. section of sponge; 
B, part of a digestive sac; C, one cell from a digestive sac. 


lets for these currents. Along the passageways from 
these outer holes (inhalent pores) to the larger holes 
(oscula) there are enlargements which act like stomachs, 
that is, they take up the food as it passes along in the 
currents of water. The endoderm cells which line 






ONE-CELLED ANIMALS AND SPONGES. 


125 


these cavities are provided with flagella which by their 
constant movement keep the water moving along from 
the inhalent to the exhalent openings. As the water 
passes along it brings 
within reach of t h e 



flagella minute animals 
and plants which are 
seized and pushed back 
into the cells where 
they are dissolved and 
assimilated in much 
the same way as the 
food of the Amoeba is 
assimilated in its cell. 



The breathing, too, is 

carried on by the indi- Fig - 109.— Sponge Spicules, 

vidual cells as in the 

Amoeba. Nutriment from the endoderm cells is passed 
along from cell to cell to nourish the rest of the body. 
From this nutriment the material for building the 
skeleton is secreted. This skeleton is often in the 
shape of spicules of hard material. Spicules may be 
calcareous, silicious , or horny , producing these three 
kinds of sponges. Only the horny or keratose sponges 
are of any commerical use. 

So nearly independent are the individual cells com¬ 
posing the sponge-structure that if a few of them be 
separated from the original body, they go on living 
and divide and subdivide, making new cells and build¬ 
ing the structure of a new sponge. If a living sponge 
be cut into hundreds of pieces, each piece grows into 
an independent animal. 

Such an aggregate of cells may be considered as 
only a transition step between a Protozoon and a 
many-celled animal of more highly specialized struc¬ 
ture. Hence some naturalists have classed sponges as 
Protozoa, some make a separate sub-kingdom Porifera, 
while others class them with the sub-kingdom Ccelen- 













126 


ANIMAL ACTIVITIES. 


terata. For our purpose it seems best to regard the 
Porifera as a separate sub-kingdom. 

Questions, i. What force propels the water through 
the canals in a sponge ? 

2. Write the functions of the sponge in columns as 
we have previously written the functions of other 
animals. 

3. In what respects does the sponge resemble the 
Paramecium ? 

4. How does a sponge differ from an Amoeba ? 

5. Where are sponges found ? 

6. Why are sponges called animals rather than 
plants ? 

Topics for Reports. Chalk. Tripolite. The Dis¬ 
covery of the Microscope. How to use a Microscope. 
Sponge-fisheries. 


VOCABULARY. 


An i mal'cule (Lat. dim. of ani¬ 
mal , from anima , breath), a 
very small animal. 

As sim i la'tion (Lat. ad, to, and 
similis, like), the process of 
making digested food into living 
tissue. 

Cal ca're ous (Lat. calx , lime), 
made of carbonate of calcium. 

Cell (Lat. cella, a small room), a 
bit of living protoplasm contain¬ 
ing a nucleus. 

Cil'i a (Lat. pi. of cilium , a hair), 
hair-like bodies capable of rapid 
movement. 

Ec'to derm (Gr. ektos , outside, and 
derma , skin), the outer layer of 
cells in a sponge. 

Ec'to sarc (Gr. ektos , and sarx, 
flesh), the outer film surround¬ 
ing one of the Protozoa. 

En'do derm (Gr. endon, within, 
and derma), the inner layer of 
cells in a sponge, the layer 
which forms the lining of the 
digestive channels. 


Fis'sion (Lat. fissus, a cleft), the 
process of reproducing by cell- 
division. 

Fo ram i nif'e ra (Lat. foramen , a 
hole, and fero, to carry), Proto¬ 
zoa having shells punctured with 
many small holes. 

In fu so'ri a (Lat. pi. of infusori¬ 
um, an infusion), Protozoa mov¬ 
ing by means of cilia. 

Ker'a tose (Gr. keras , a horn), 
horn-like. 

Mesoderm (Gr. mesos, middle, 
and derma), the part between 
ectoderm and endoderm. 

Nu'cle us (Lat. dim. of nux, nut), 
a denser bit of protoplasm in a 
cell. 

Os'cu lum (Lat. dim. of os, mouth), 
a minute pore or mouth. 

Pseu do po dium (Gr. pseudos, 
false, and fous, foot), a project¬ 
ing portion of an Amoeba’s cell, 
a false foot. 

Pro'to plasm (Gr. protos, first, and 
| plastna , form), the substance of 



ONE-CELLED ANIMALS AND SPONGES. 


127 


which living cells are mainly- 
composed. 

Rhi zop'o da (Gr. rkiza , root, and 
pons), Protozoa having pseudo¬ 
podia for locomotion. 

Sar code (Gr. sarx, flesh) the fleshy 
part of a sponge. 


Si li'cious (Lat. si/ex, flint), made 
of a substance like glass. 

Spic'ule (Lat. dim. of spicum, a 
spike), a bit of hard material 
formed in the tissues of sponges 
and other lower animals. 



CHAPTER XII. 


THE HYDRA AND SOME CCELENTERATES WHICH 
LIVE IN COLONIES. 

Fresh-water Hydra. In warm weather hydra may 
be found near the surface of fresh water on leaves or 
sticks or attached to the stems of aquatic plants. If 
such leaves or plants be collected and placed in a plate, 
or jar of water in the sunlight, hydra may be seen in a 
short time. As soon as they have been found, transfer 
them with the plants on which they feed to an aquarium, 
where they may be easily kept all winter. They feed 
on cyclops, daphnia, and other small crustaceans. 
These are commonly found in the same places as the 
hydra and probably will appear in the water with the 
leaves collected. If they do not appear keep on col¬ 
lecting dead leaves from different localities until they 
are found. Both hydra and its food may be found 
almost anywhere if patience and care be used in collect¬ 
ing. When wanted for use it is easy to transfer hydras 
to a watch-glass by removing them from the side of the 
aquarium with a knife and dipping them out with a 
glass tube. 

Note the appearance of hydras as you see them in 
the aquarium. 

What is their size ? their shape ? Do all have the 
same shape ? 

Look for branches and buds. How many do you 
find on any hydra ? 

What is the color of hydra ? 

What movements can the hydra make ? 


128 


HYDRA AND CCELENTERATES. 


129 


In what part of the aquarium with reference to light 
are they most abundant ? 

Place a hydra in a watch-glass in water and observe 
it more closely with a magnifying glass. What do 
you see ? 

Watch one take a particle of food. 

Notice the foot, the body, the tentacles, the hypo- 
stome, and the mouth. 

What happens when you touch a tentacle ? 

In what respects does the hydra resemble the 
sponge ? 

How do the two animals differ ? 

Cut a hydra in several pieces and place these in a 
dish in clear water. Watch the pieces for several 
days. 

Place a single budding hydra in a battery-jar with 
water and food. At frequent intervals count the 
number of hydras present. 

Summary of Drawings. ( a ) A single hydra with 
tentacles showing X 10. 

(< b ) A hydra with tentacles contracted X 

( c ) A single hydra showing buds and branches X 10. 

(1 d ) Several hydras in different positions taken in 
locomotion X 10. 

The Activities of the Hydra. Taking Food. The 

hydra uses the tentacles surrounding the upper end of 
its cylindrical body for the purpose of seizing its prey 
and conveying it to the mouth. These tentacles are 
covered with minute nettling-cells which paralyze the 
small crustacean as soon as he is seized. These cells 
have within them a very minute coiled thread which is 
uncoiled when the cell is touched. This thread pierces 
the victim which has been unwittingly the cause of the 
uncoiling and poisons the part it pierces. These 
nettling-cells are sometimes called thread-cells or 
lasso-cells. They are characteristic specializations of 
the sub-kingdom C&lenterata . 

Digestion. The food after being pushed into the 


130 


ANIMAL ACTIVITIES. 



mouth by the tentacles passes into the body-cavity, 
which is also a stomach. 

The hydra is really a bag, being hollow, even out in 
the tentacles. The food moves about inside of this 
bag and is dissolved there. The 
hard and useless parts of the food 
are pushed out through the mouth, 
which is the only opening into the 
bag. The nutriment is assimi¬ 
lated by the cells lining the bag 
or stomach-cavity. This lining 
is called the endoderm and its 
cells are very little differentiated 
from the ectoderm, or outside 
cells. 

Respiration. The cells of the 
hydra breathe independently, as 
do those of the sponge. 

Reproduction. If the hydra is 
divided into several pieces each 
piece reproduces the missing parts 
and becomes an active individual. A common method 
of reproduction is by the process of budding. The buds 
appear first as swellings along the sides of the parent 
hydra; they gradually develop a row of tentacles; a 
mouth breaks through into the common cavity of both 
parent and offspring; the base of the branch into which 
the bud has now grown constricts and finally breaks 
away entirely from the parent; and the hydra, free and 
independent, seeks its own place of feeding. 

But the hydra also reproduces by means of eggs. 
These appear as swellings on the side of the parent in 
much the same way as the buds just mentioned. Above 
the egg just below the fentacles another swelling 
appears. This contains the fertilizing or male cells 
{sperms'). The swelling containing the sperm-cells is 
called the testis. The ova as they mature float away 
into the water, as do also the sperms. A sperm swims 


F ig. i io. —Thread-cells 
{highly magnified ). 




HYDRA AND CCELENTERATES. 


1 3 1 

actively about and finally coalesces with an ovum from 
another hydra. This process is called cross-fertiliza¬ 
tion. Animals which produce in the same individual 
both ova and sperms are said to be hermaphrodite. 
We can see that this cross-fertilization does not differ 
materially from that already described as occurring in 
the white clover. The eggs after fertilization are called 
oosperms. These oosperms develop into hydras like 
the parents. In the autumn, eggs are produced with 



thick, hard shells to withstand the cold and thus pre¬ 
serve the species until spring. 

Discovery. The hydra has no nervous system, 
though a few nerve-cells are developed. It is sensitive 
to light and extremely so to touch. 

Movement. The hydra moves without muscles. It 
can move by pushing its sucking-disk or foot along the 
leaf to which it is attached or it can march by somer¬ 
saults to its destination. The tentacles seem to move 
at will. 

The Hydractinia. Division of Labor. A salt¬ 
water animal which resembles the hydra is Hydractinia . 












132 


ANIMAL ACTIVITIES. 


It is often found attached to snail-shells inhabited by 
hermit-crabs. The individuals live in a colony and 
vary according to the work each has to do. They all 
grow together at the base, and so are connected by 
living tissue through which digested food may be passed 
from one to another. 

Here one individual (a) does the eating for the colony 
with the help of others like himself; another ( 6 ) attends 
entirely to the work of reproduction ; while still another 
(c) protects the colony from enemies. These hydra¬ 
like individuals, which are not strictly individuals 
because they do not lead an independent existence, 
are called zooids. Such an assembly of zooids is called 



Fig. i 12_Hydractinia ( magnified .). After Agassiz. A, male colony; 

B, female colony; a, feeding zooid; tentacles; b, reproductive 
zooid; c, protective zooid; d , e, f, g , h , i, stages of jelly-fish. 


a colony. Again we notice the setting apart or differ¬ 
entiating of zooids to perform each its own work. 

At the base of the zooids of Hydractinia a hard skele¬ 
ton is built, which resembles coral in its nature. 

Commensalism. As stated above, the Hydractinia 
is commonly found on shells inhabited by hermit-crabs. 
The Hydractinia colony is thus carried about and 
brought constantly into contact with a new food-supply. 







HYDRA AND CCELENTERATES . 


133 


The hermit-crab, on the other hand, is probably pro¬ 
tected from enemies by the moss-like growth on its 
shell. The two animals seem to find this association 
mutually advantageous. The word commensalism is 
applied to animals living together in this manner. 

Campanularian Hydroids. These colonies may be 
easily collected, being found attached to logs or sea¬ 
weed, just at the level of low tide. The zooids may 
be stained with carmine solution for the purpose of 
making out the parts more easily. If there is time the 
pupils should note the following points: 

Examine a specimen, natural size, kept in formalin. 
How does it resemble a hydra ? 

Do you find bilateral symmetry, either in the colony 
or the zooids ? 

Place a specimen in a watch-glass and examine it 
with a simple microscope. How many kinds of zooids 
do you see ? 

In the feeding zooids can you see tentacles, hypo- 
stome, and a thickened body in a protecting, bell¬ 
shaped case ? 

In other longer cases in the axils of branches do 
you see a number of round masses ? 

These are really buds growing in the reproductive 
zooid. When fully mature, these masses float out at 
the top of the protecting case and swim away as small 
jelly-fishes. 

Examine both kinds of zooids, using a compound 
microscope. 

Summary of Drawings. (a) A Campanularian 

colony of natural size. 

( b ) A single feeding zooid slightly magnified. 

(c) A single reproductive zooid slightly magnified. 

Alternation of Generations. The jelly-fish which 

swim away from the reproductive zooid do not attach 
themselves to rocks, but remain free as long as they 
live. They are umbrella-shaped bodies, the mouth 
being at the end of the handle, their shape being like 


134 


ANIMAL ACTIVITIES. 


that of an inverted hydra, with a greatly overgrown foot 
forming the covering of the umbrella. These jelly-fish 
are often called medusae, because in some similar forms 
the long tentacles around the edges of the umbrella 
covering are supposed to resemble the snaky locks of 
the mythical monster. The tentacles surrounding the 
umbrella of the Campanularian medusae are not large, 
but they have at their bases minute spots connected 
with nerve-masses. These are thought to be eyes or 




Fig. i 13.— Medusae of Campanularium Hydroid (Eucope diaphana). a, 
whole colony, one half natural size; b, single zooid magnified; 
A , young medusa magnified; B , adult medusa magnified. After 
Agassiz. 


ears. These jelly-fishes swim through the water with 
a slow flapping of the umbrella edges. 

After a time eggs are produced which float out into 
the water and produce, not jelly-fish, but the branching, 
fixed Campanularians. Thus the young resemble the 
grand-parents instead of the parents. The children of 
these young, however, resemble the jelly-fish. Such 
a phenomenon is not uncommon in the animal world 
and is called alternation of generations. 

Scyphozoa. Besides the jelly-fish just described 
there are other free-swimming medusae whose origin is 



HYDRA AND CCELENTERATES . 


135 


somewhat different. The egg from one of these medusae 
grows into a fixed, more or less hydra-like form which 
at maturity splits horizontally into a number of saucer¬ 
like disks. These finally break away and become the 
large jelly-fish we so commonly see in salt water (Fig. 
114). 

Sea-anemones. In its cylindrical shape, the position 
of its mouth and tentacles, and in possessing thread- 



Fig. 114. —The Origin of a Scyphozoan Jelly-fish (Medusa aurita). 
a , adult; b, c, d , e, f, g , earlier stages. 


cells, the sea-anemone resembles the hydra. The 
larger size of the sea-anemone makes it easy to study 
in localities where it can be used alive. 

In the anemone the hollow body is traversed by 
radiating partitions called mesenteries. These serve 
to increase the area exposed to digested food. There 
is no hypostome present, and the internal cavity is 
reached by a passageway called the gullet. 

Corals . The coral animals resemble the sea-anemone 
in structure. They differ chiefly in the fact that they 
deposit a hard skeleton. In the more common corals 
the skeleton shows septa corresponding to the mesen¬ 
teries in the living animal. These animals live for the 
most part in colonies, the single individuals, or polyps, 
being connected at their bases in such a way that nutri¬ 
ment may pass from one to another. The examination 


136 


ANIMAL ACTIVITIES . 


of coral skeletons shows some facts concerning coral 
growth. 

Examine the skeleton of Fungia. Remember that 
this is the skeleton of an animal something like the 


Fig. 




B 


115.—The Structure of a Sea-anemone. A , longitudinal section; 
B , transverse section; m, mouth; o, eggs; /, tentacle. 


sea-anemone. What are some peculiarities of this 
skeleton ? 

Examine pieces of Galaxea skeleton. How does 
Galaxea differ from Fungia ? 

Count the septa in several tubes of Galaxea. How 
many ? The parts of the tubes projecting above the 
general structure are called the thecce. 

Examine a branch of Madrepora. How does this 
differ from Fungia ? from Galaxea ? 

Do you find thecae and septa in Madrepora ? 

Were all the polyps of the same size ? 

How did the branches in Madrepora arise ? 

Were the lateral polyps connected with the central 
polyps ? Use branches sawed longitudinally to show 
this point. 

How did the lateral polyps arise in the course of 
growth ? 

How did the colony develop from a single polyp ? 

Summary of Drawings, (a) Fungia skeleton, nat¬ 
ural size. 

( b) Galaxea skeleton showing several tubes X 3- 






HYDRA AND CCELENTERATES. 


137 


(?) Two tubes of Galaxea skeleton with outline 
sketch of the polyps that built the skeleton as you 
think they may have appeared X 5 - 

( d ) Branches of Madrepora skeleton, natural size. 

(e) Longitudinal section of branch of Madrepora 
skeleton. 

Other Coral-like Animals. There are many other 
kinds of corals and coral-like animals. The red coral 
of commerce is produced by polyps which deposit the 
solid matter in such a way that no traces of septa show 
in the skeleton. Something like these red-coral polyps 
are those which deposit a horny substance instead of 
calcareous matter, forming the sea-fans, sea-pens, and 
other similar growths of tropical regions. 

Characteristics of the Ccelenterates. The Coelen- 
terates may be said to be animals having hollow cylin¬ 
drical bodies provided with a single opening at one 
end. This opening is commonly surrounded by tenta¬ 
cles and these are provided with nettling-cells. 

Classes of Ccelenterates. Animals like the hydra, 
having the whole body-cavity used as a stomach, and 
bearing a hypostome at the mouth-end of the body are 
called Hydrozoa. 

Sea-anemones and coral polyps have the hypostome 
inverted to form a gullet. Radiating partitions or 
mesenteries are found in the body-cavity. These 
animals are called Actinozoa . 

Our largest jelly-fishes, briefly described on page 133, 
are called Scyphozoci. 

Laboratory Exercise for Review. Using specimens 
in numbered bottles or boxes, as indicated on page 
113, write in note-books, or on paper, as fully as you 
can concerning the topics indicated below. Specimens 
not previously seen by the pupil are especially valuable 
for this work.* 

* Of course all these activities cannot be inferred correctly from 
structure in every case, but the attempt to make the inference is valu¬ 
able, and success is more frequent than failure. 



ANIMAL ACTIVITIES. 


138 

1. Habitat. 

2. Mode of Locomotion. 

3. Mode of Breathing. 

4. Kind of Food Used. 

5. Classification. 

Topics for Reports. The Portuguese Man-of-war. 
Sea-anemones. Coral Islands. The Origin of Atolls. 
Coral Reefs. How Corals Have Helped to Build 
Florida. The Origin of Plants and Animals on Coral 
Islands. Examples of Alternation of Generation. 
Commensalism. Colonies. Experiences while Col¬ 
lecting Ccelenterates. Parasitism. Symbiosis. 


VOCABULARY. 


Cam pan u la'ri an (Lat. dim. of 
campana, a bell), a kind of hy- 
droid whose feeding zooids live 
in a bell-shaped case. 

Com.men'sal ism (Lat. cum , to¬ 
gether, and mensa, a table), a 
state of living together for mutu¬ 
al advantage, as in the case of the 
hermit-crab and hydractinia. 

Her maph'ro dite (Gr. Hermaphro- 
ditos , the son of Hermes and 
Aphrodite), having both male 
and female reproductive cells in 
the same animal. 

Hy'dranth (Gr. hydor , water), one 
of the nutritine zooids of a hy- 
droid colony. 

Hy'po stome (Gr. hypo, under, and 
stoma , a mouth), the part of a 
hydroid animai bearing the 
mouth at its summit. 

Las'so cell (Lat. laqueus , a snare), 
a sensitive nettling-cell contain¬ 
ing a coiled thread. 


Me du'sa (Lat. Medusa, one of the 
Gorgons), an umbrella-shaped, 
free-swimming jelly-fish. 

Mes'en te ry (Gr. mesos , middle, 
and enteron , intestine), one of 
the radiating walls in the body 
of a polyp. 

O'vum (Lat. ovum), an egg. 

Pol'yp (Gr .polys, many, and/owj, 
foot), a feeding zooid of a hy¬ 
droid or coral-forming colony. 

Sep'tum (Lat. septum, a fence), a 
radiating portion of a coral skel¬ 
eton. 

Ten'ta clc (Lat. tento , to try to 
hold), a feeler around the mouth 
of a coelenterate. 

The'ca (Gr. theke , a case), a 
portion of a coral skeleton. 

Zo'oid (Gr. zoon, an animal, and 
oid, like), one of the members of 
a coelenterate colony. 




Make a table like this in note-book and fill the spaces by referring to work 

previously done. 


HYDRA AND CCELENTERATES, 


139 














































CHAPTER XIII. 


THE STARFISH AND CLOSELY RELATED ANIMALS. 

The Starfish. The common starfish (Asterias vul¬ 
garis) may be easily found at low tide along the New 
England coast. To obtain the dried specimens for 
study, kill the animal by immersing it in warm fresh 
water. It may then be preserved by hardening it in 
alcohol or in boiling water and drying quickly, or by 
packing in salt. If possible get a living starfish and 
place it in a pail of salt water. 

How does the starfish move ? Observe the ambu- 
lacral feet. 

Do you see the eye-spot at the end of each arm ? 

Where is the madreporic body ? 

Is the animal bilateral ? 

Is each ray bilateral ? 

Are all of the rays of the same size ? How do you 
explain any differences ? 

Are any of the spines movable ? 

Which is the oral and which the aboral surface ? 

With a magnifying glass examine the aboral surface 
for the purpose of finding the minute pincer-like bodies 
called p e dicellar ice. 

Can you find projections of the skin used in breath- 
ing ? 

Examine a dried specimen. 

Are all the spines of the same shape ? 

How many kinds of spines do you find ? 

How many kinds of plates do you find ? 




THE STARFISH AND CLOSELY RELATED ANIMALS. 141 

The walking, or ambulacral, surface is called the 
ambulacrcil area. 

How many rows of ambulacral plates in each ray ? 
How many rows in all ? 

Do the ambulacral feet pass through these plates or 
between them ? 

The regular plates situated on either side of the 
ambulacral areas are called inter ambulacral plates , and 
the surfaces they cover are called inter ambulacral 
areas. How many rows of interambulacral plates do 
you find in each ray ? How many rows in all ? 

How do the spines on these plates differ from those 
on the irregular plates of the aboral surface ? 

The plates on the aboral surface may be called 
body-plates. Can you find the single plate with its 
ambulacral foot at the end of each ray ? 

With a partly dissected specimen, which has been 
prepared by hardening in alcohol, laying open the 
upper or aboral surface of one of the rays and removing 
the digestive organs, notice the ampullae or internal 
enlargements of the ambulacral feet. What is the use 
of the ampullae in locomotion ? 

These ampullae are connected with a tube running 
along the ray in the angle made by the two rows of 
ambulacral plates. Trace this tube, which supplies the 
ambulacral feet with water, up to the tube running 
around the mouth. Find the stone canal connecting 
this tube with the madreporic body. What do you 
think may be a use of the madreporic body ? 

Examine portions of the skeleton of a starfish which 
have been decalcified by allowing them to soak in 
about ten per cent, nitric acid for a few days. Compare 
these with similar portions which have been treated 
with weak caustic potash until the fleshy matter has 
been removed. Are the plates formed inside of the 
fleshy skin or outside of it ? 

Write resemblances and differences for starfish and 
hydra. 


142 


ANIMAL ACTIVITIES. 


Compare this starfish with the brittle starfish. 

Summary of Drawings, (a) Sketch of a living 
starfish. 

(b) Sketch of a portion of an ambulacral area show¬ 
ing the relative positions of the plates and the openings 
for the ambulacral feet. 

( c ) Cross-section of an arm to show the relative posi¬ 
tion of feet, water-tube, plates, and spines. 

( d ) Ambulacral feet with ampullae. 

( e ) Sketch of a brittle starfish. 

Activities of the Starfish. The starfish belongs to 
the sub-kingdom Echinodermata, animals having hard 


plates in the skin. 
Their movements 
are slow and all 
their activities are of 
a low order, yet they 
are more highly 
specialized than the 
Ccelenterates w e 
have just been con¬ 
sidering. 



Taking Food. 

The mouth of the 
starfish is situated 
on the under side, 
hence this side is 


Fig. ii6.— A Starfish. After Agassiz. called the oral side. 


There are no teeth, 


yet the starfish lives on oysters, clams, mussels, and 
other hard-shelled animals. The stomach is an 
elastic bag which fills the central part of the body 
and extends into all the arms or rays, thus making the 
shell simply a protection for this branching, walking 
stomach. This stomach secretes a fluid which par¬ 
tially paralyzes its prey. If a mussel is too large to 
pass through the mouth, the starfish stretches a part 
of its stomach outside of its body, and enfolds its 


THE STARFISH AND CLOSELY RELATED ANIMALS . 143 

victim until the shell opens and the contents can be 
sucked out. 

Nutrition. Outside the stomach, throughout' the 
cavities in the rays there is a glandular mass, the liver, 
which secretes a digestive fluid and pours it into the. 
stomach. Here the food is digested and the nutriment 
absorbed. There is a very short intestine opening 
opposite the mouth. It is so small in diameter that 
the waste of the food cannot pass through it, and must 
therefore be ejected through the mouth. 

Respiration. For the most part breathing takes 
place at all parts of the body, but there are folds of the 
skin over the aboral surface which are supposed to act 
somewhat like gills. 

Reproduction. The reproductive organs, of which 
there are two in each ray, lie on the floor of the ray; 
their ducts opening in the angles between the rays. 
These openings are called the genital openings. After 
the eggs of the female and the sperms of the male 
have been discharged into the water, the eggs are fer¬ 
tilized by the sperms. From these fertilized eggs de¬ 
velop young starfish, which are at first bilateral, and 
bear no resemblance to their parents. 

Discovery. The only specialized sense-organs are 
the eye-spots at the ends of the rays. The -nervous 
system consists of a nerve around the mouth with a 
branch extending into each ray and ending in the eye- 
spot just mentioned. The sense of feeling is apparently 
dull, and the starfish seems to suffer no hardship by 
the deprivation of one or two of its rays, which quickly 
grow again when once broken off. 

Movements. The starfish and its relatives have a 
method of locomotion very different from other animals. 
Along the oral surface of the rays are the cylindrical 
tube-feet, or ambulacral feet, bearing suckers at their 
extremities. These tubes extend through the skeleton 
into the body-cavity, where they enlarge into bulbs 
called ampulla. Each bulb connects by a small tube 


144 


ANIMAL ACTIVITIES. 


with a larger tube running lengthwise of the ray, and 
this in turn connects with a tube surrounding the 
mouth. With this oral tube the radiating tubes all 
unite and from this there extends the stone canal 
(another tube) reaching to the madreporic body on the 
aboral surface. The ambulacral feet have muscular 
walls. The madreporic body is pierced with minute 
holes through which water can enter the water-system. 



Fig. i i 7.—A Brittle Starfish. 


When the starfish wishes to advance, some of the am¬ 
bulacral feet are elongated in the direction of progres¬ 
sion by squeezing the ampullae and forcing the water 
into the feet. When the feet are fully extended the 
sucker at the end of each foot fastens itself to the rock, 
or other support near, and the longitudinal muscles of 
the tube contract, shortening the ambulacral foot and 
pulling the starfish to the rock. 


THE STARFISH AND CLOSELY RELATED ANIMALS. 145 


The Sea-urchin. If possible get a living sea-urchin 
and watch its movements in a pail of salt water, or 
better, in a salt-water aquarium. 

What is the shape of the body ? 

Do you find oral and aboral surfaces ? 

What is the shape of the spines ? How do they 
move ? 

Do you find the ambulacral feet ? 

Examine the mouth and notice the manner of feed¬ 
ing. 

Hold the living animal in the hand and observe its 
mode of locomotion. 

Place it upside down in the water and watch it. 

Does it have bilateral symmetry or any kind of sym¬ 
metry ? 

Examine the test or shell which has been freed from 
spines. 

How can you tell the ambulacral from the inter- 
ambulacral plates ? 

How many rows of each kind of plates do you find ? 

What is the shape of these plates ? 

Look at broken pieces of tests. 

Do you find a single plate or tentacle at the end of 
each ambulacral area, as in the starfish (ocular 
plates) ? 

At the ends of the interambulacral areas do you find 
the genital openings ? How many do you find ? 

The small plates, in the circle surrounded by the 
genital plates, correspond to what plates in the starfish ? 

Do you find the madreporic body ? 

What changes would have to occur in the body of 
the starfish to give it the form of the sea-urchin ? 

What parts of the sea-urchin are homologous with 
parts of the starfish ? 

Examine the teeth. How many teeth do you find ? 

Write resemblances and differences for starfish and 
sea-urchin. 

Compare a sea-cucumber with a sea-urchin. 


146 


ANIMAL ACTIVITIES. 


Summary of Drawings, (a) A living sea-urchin, 
natural size. 

($) A single spine showing mode of attachment to 
the shell. 

(c) Several ambulacral and interambulacral plates. 

( d ) External form of a sea-cucumber. 


A B 

Fig. 118.— The Structure of a Sea-urchin. A, interior of shell; B, 
teeth. 

Activities of the Sea-urchin. The activities of the 
sea-urchin resemble those of the starfish. One pecul¬ 
iarity deserves mention. The mouth of the sea-urchin 
is provided with a complicated 
arrangement of teeth, five in 
number, uniting at a point. 
This whole apparatus is called 
Aristotle’s lantern in honor of 
the philosopher who first de¬ 
scribed it. With these teeth and 
possibly by the aid of oral secre¬ 
tions the sea-urchin is enabled 
to burrow into solid rock. 

Other Echinoderms. Sea- 
cucumbers of many kinds, the 
worm-like Synapta with i t s 
anchor-shaped plates, the great 
variety of starfishes, sand-dol- 
lars, Crinoids both fossil and present, with other less 
common forms all bear a striking resemblance to the 
two forms studied. 








THE STARFISH AND CLOSELY RELATED ANIMALS. 147 


Characteristics of Echinodermata. This sub-king¬ 
dom enjoys the distinction of being the most exclusive 
division of the animal kingdom. These animals secrete 
bony plates in the skin; they have marked radiate 
structure, almost always being divided into five radiat¬ 
ing parts. With the radiate structure we may also 
trace a bilateral condition. (In the case of the starfish 
this condition may be seen by drawing a line through 
the madreporic body and the opposite ray.) The 
water-system with its ambulacral feet is peculiar to this 
sub-kingdom. All are marine. 

Topics for Reports. The Burrowing of Sea-urchins. 
Sea-cucumber as Food. Radiate Structure. Where I 
Have Seen Echinoderms. The Senses in a Starfish. 
Young Starfishes. Basket-fish. Stone-lilies. 


VOCABULARY 


Ab o'ral (Lat. ab , from, and os, 
mouth), the surface opposite the 
mouth. 

Am bu la'cral (Lat. ambulo , to 
walk about), a word applied to 
the walking areas of Echino¬ 
derms. 

Am pul'la, pi. ampulla (Lat. 
ampulla , a flask), the enlarged 
end of one of the tube-feet of 
an Echinoderm. 

De cal'ci fy (Lat. de, from, and 
calx , lime), to remove the calca¬ 
reous matter. 

Gen'i tal o pen mgs, the openings 


for the passage of eggs and sperm 
in starfishes and sea-urchins. 

Mad re por'ic body, a hard plate 
pierced with holes through 
which water filters into the tube- 
feet of a starfish or sea-urchin. 

O'ral (Lat. os, the mouth), pertain¬ 
ing to the mouth. 

Ped i cel la'ri a (Lat. pediculus , a 
small foot or stalk), a minute 
pincer-like organ on the skin of 
an Echinoderm. 

Ra'di ate (Lat. radius, a ray), 
having the parts regularly ar¬ 
ranged around a centre. 



CHAPTER XIV. 


THE EARTHWORM AND HIS WORK. 

The earthworm or'angleworm belongs to the sub¬ 
kingdom Vermes. It also belongs to the class Annu- 
lata, which includes the most highly organized and 
most intelligent animals belonging to this sub-kingdom. 
In studying it we must note how it differs from any or 
all of the Arthropoda, and discover if possible why 
naturalists have not classified it with this sub-kingdom. 

The earthworm may be easily observed alive by 
placing several individuals in a glass jar with loam and 
dead leaves, and occasionally feeding them with bits 
of meat or vegetables. 

Is the body bilateral ? 

Can you distinguish a head ? a head end ? a neck ? 
a dorsal and ventral surface ? 

Is the body anywhere flattened ? 

Are there any divisions in the body like those in the 
Arthropoda ? 

Are there any jointed appendages ? 

Do you find any eyes ? Is the worm sensitive to 
touch ? to light ? to strong odors ? to irritating fluids ? 

While the worm is feeding can you see any teeth ? 
Do you see something which looks like a proboscis ? 

Do you see the red blood-vessel near the dorsal sur¬ 
face ? 

Earthworms tanned by the use of chromic acid make 
good specimens for class use. They may be prepared 
as follows: Place the worms in dilute alcohol for three 
or four days and then transfer them to strong alcohol, 

148 


THE EARTHWORM AND HIS WORK . 


149 


where they may remain for several weeks. Then put 
them in a one per cent, solution of chromic acid for five 
or six days. Remove 
them from this' solu¬ 
tion, wash them thor¬ 
oughly in water and 
place them in a dish 
with turpentine, al¬ 
lowing them to re¬ 
main there for a few 
days longer. They 
may then be dried, 
when they are ready 
for use. The worms should be spread out in flat- 
bottomed dishes during the processes of tanning. 
With specimens thus prepared or simply hardened in 
alcohol, the class should write the answers to the fol¬ 
lowing questions: 

Do the worms all have the same number of seg¬ 
ments ? 

Do you find several rings together which seem to be 
enlarged ? This is the clitellum or reproductive girdle. 

How many segments from the clitellum to the head 
end ? 

Is the body of the angleworm smooth ? Does it 
appear more rough when the finger is moved in any 
special direction ? The roughness is caused by bristles 
or setcz. Do they all point in the same direction ? 

How many rows of setae along the body ? How 
many setae on a single segment ? 

Does the worm have an internal skeleton ? Does a 
thin cuticle separate easily from the body of a worm 
which has been soaking in water for a time ? 

Can you make out the shape of the segment in front 
of the mouth ? 

Summary of Drawings. ( a ) The whole worm, nat¬ 
ural size. 

(J?) The segments near the head X 6. 



Fig. 120.—An Earthworm. 




ANIMAL ACTIVITIES. 


150 

(c) A cross-section of one segment to show the setae 

X 6. 

Taking Food. The earthworm has neither hard 
mouth-parts for biting food nor a tube for sucking. Its 
mouth is simply a hole bounded 
by fleshy lips. The segment in 
front of the mouth forms a sort of 
proboscis or elongated upper lip 
which is used to push the food 
into the mouth. The food con¬ 
sists of fallen leaves or any organic 
matter found in or around its bur¬ 
row. Decaying vegetable matter forms the greater 
part of its food, and if it cannot get decayed leaves it can 
pour out of the mouth a fluid which makes the leaf 
decay and blacken at once. Since the worm gets much 
of its food beneath the surface of the earth, it builds a 
burrow for its home. Such a burrow is a plain hole 
usually slanting from the surface down to a depth of 
four or five feet, always extending below the frost of 
winter. At the bottom of this hole is a small round 
room carefully lined with stones or seeds. In making 
this burrow the worm not only eats the vegetable matter 



Fig. 121.—A Worm’s 
Setae. 



Fig. 122.—Worm-casts. 


in the ground but swallows the earth as fast as he 
excavates it, thus mixing his food with loam. 

Nutrition. The worm has no teeth and no jaws; so 
his food passes down the gullet or oesophagus to an 
enlargement of the alimentary canal called the crop. 




THE EARTHWORM AND HIS WORK. 151 

Next it goes on to the gizzard, which is filled with little 
stones to make a mill for grinding the food. After 
being ground, the food passes into the intestine, where 
the nutritious matters are taken into the blood and 
carried to the tissues of the body, while the part which 
cannot be digested is cast out at the end of the body, 
usually near the opening of the worm’s burrow. The 
blood which carries the nutritious matter to the parts 
where it is needed is of a reddish color, but the color 
is in the liquid part of the blood and not in the corpus¬ 
cles, as is the case in our own bodies. 

Respiration. An examination of the earthworm’s 
body reveals neither spiracles nor gills. In fact it has 
no breathing organ, but takes oxygen from the air at 
all parts of its skin and sends out or excretes carbon 
dioxide and other impurities at the same time. The 
blood-vessels are so near the surface that the necessary 
interchange of gases can easily take place as long as 
the worm’s skin is moist. Worms cannot live long in 
the sunlight or in dry sand because they cannot breathe 
under such conditions. 

Reproduction. On the under side of the fourteenth 
and fifteenth segments in a common species are to be 
found some small openings which lead to the ovaries or 
egg-producing organs. Several segments in front of 
these, there are tiny holes in the grooves between the 
segments. These open into receptacles containing the 
male cells or sperms. 

When the time for depositing eggs arrives certain 
glands of the clitellum become very active and pour 
out on the surface of the body a fluid which hardens 
into a tough membrane, making a girdle around the 
body, the reproductive girdle. A jelly-like liquid 
remains between the girdle and the body while it is 
gradually pushed forward. When the girdle passes the 
openings to the ovaries the eggs are discharged into it, 
and when it passes the segments from nine to eleven 
the sperms pass into the fluid with the eggs. The 


ANIMAL ACTIVITIES. 


x 5 2 

girdle then passes over the head and closes at both 
ends, forming a capsule containing the reproductive 
cells. Here fertilization takes place, and the eggs 
hatch finally into little worms which rapidly grow by 
the addition of new segments. 

Discovery. We find no eyes, ears, or other organs 
of sense on examining the earthworm, yet we know 
that he has to some slight extent a sense of smell, for 
he enjoys the smell of onions, cabbages, and other 
dainty articles of earthworm diet. Possibly, too, he 
can hear a little, for he is disturbed by sounds which 
shake the earth near his burrow, though utterly dis¬ 
regarding the loudest noises made in the air above him. 
Although without eyes he can tell daylight from dark¬ 
ness; the power of doing this is said to reside in the 
first few segments of his body in which his brain is 
found. He is probably somewhat sensitive to light in 
all segments of his body. 

His sense of touch is keenest of all and, indeed, his 
whole body seems to be a sort of feeler. 

Movements. The earthworm doubtless controls his 
own movements to a considerable extent. He even 
shows signs of intelligence, though of a very low order. 
The most brilliant thing the earthworm does is to plug 
up the opening of his burrow to hide it from his 
enemies. For this purpose he selects his material with 
some care. 

Leaves, bits of paper, twigs, wool, and sometimes 
stones are used by the worm to make this plug, or door, 
to his hole. He seizes with his lips the substances to 
be used and fits them neatly to the mouth of the 
burrow. When he uses a leaf he drags it in by the 
part best suited by its shape to fit the place intended 
for it. Mr. Darwin noticed that sometimes a worm 
would let go a leaf and then try a new way of pulling 
it into his hole. 

The worm also moves up and down his burow at 
will, and if necessary he can travel some distance from 


THE EARTHWORM AND HIS WORK. 153 

home, crawling - over very difficult roads and even 
scaling perpendicular walls. The controlling mechan¬ 
ism for these movements lies in a small brain situated 
above the oesophagus and hence sometimes called the 
supracesophageal ganglion, and in a series of ganglia 
lying under the alimentary canal, a pair in each seg¬ 
ment. These ganglia are connected with each other 
and with the brain by nerves, and branches ramify from 
them to all parts of the body. This arrangement of 
nerve-masses along the ventral portion of the body is 
decidedly advantageous to a crawling animal, giving 
him constant information concerning the ground over 
which he travels. 

Locomotion in the earthworm is accomplished by 
the use of three sets of muscles under the control of his 
nervous system. One set of muscular fibres runs 
lengthwise of the body, another surrounds each ring, 
and a third layer sends its fibres diagonally across the 
segments. When an earthworm wishes to go forward 
he fixes his setae in the ground in such a way that his 
body cannot move backward, but will easily move for¬ 
ward. If, now, his body is already extended its full 
length, he contracts his longitudinal muscles, thus 
shortening his body and making it much thicker. He 
then contracts the circular muscles surrounding the 
segments, elongating the body and making it much 
smaller in circumference. Since the setae prevent the 
body from going backward, it must move forward. The 
setae are curved near the end to make them more useful 
in holding the body in place. The diagonal muscles 
are used in moving the body from side to side. 

The Usefulness of the Earthworm. In spite of his 
apparent insignificance the earthworm is the farmer’s 
loyal friend. He is a ploughman of ancient lineage 
and his work is most efficient. He brings to the sur¬ 
face fresh subsoil to replace the exhausted layer which 
the farmer has been cultivating. He grinds up organic 
matter and leaves it finely powdered in his castings for 


x 54 


ANIMAL ACTIVITIES. 


the use of plants. He renders the earth porous for the 
better spread of moisture and the more rapid pushing 
of plant-roots. He buries rocks far beneath the soil 
and covers old fields with fresh loam. All pupils 
should read Mr. Darwin’s book entitled “The Forma¬ 
tion of Vegetable Mould.” 

The Earthworm’s Relatives. Along with the 
earthworm are classified many animals which outwardly 
bear no resemblance to him. It sometimes seems as if 
naturalists reserved the sub-kingdom Vermes as a sort 
of waste-box in which to place all creatures not easily 
classified elsewhere. The strange ways of the Vermes 
must be studied by the help of other books. 


CHAPTER XV. 


MUSSELS AND SNAILS. 

The Fresh-water Mussel (Anodon or Unio). These 
mussels may be easily obtained on the sandy bottoms 
of fresh-water ponds or streams. A few should be 
placed in an aquarium which has a few inches of sand 
on the bottom. They do well without feeding. Little- 
neck clams make good individual specimens for the 
work here outlined. Boil the clams to harden them. 

Notice the color and shape of the shell. How many 
parts has it ? 

Do you see any markings on the outside ? What do 
these seem to indicate ? 

Does the shell seem to be covered ? Compare it 
with a dried shell. Is the entire surface covered ? 
How do you explain your observation ? The bared 
projection is called the umbo. 

How are the two parts of the shell held together ? 
Is the hinge you find at the dorsal or ventral margin of 
the valves ? How can you tell ? 

In what direction does the animal move ? How fast ? 

Is the umbo nearer the anterior or the posterior 
end ? How can you tell ? 

Find the right and left valves. 

Observe the foot. How is it used ? 

Is it at the anterior or posterior end of the body ? 

At the end opposite the foot find the fringed open¬ 
ings. When the shell is open and the animal is feed¬ 
ing comfortably, color the water directly in front of 
these openings with a little indigo or cochineal solution 

i55 


ANIMAL ACTIVITIES. 


156 

introduced by a pipette. What do you learn from this 
concerning the manner of feeding ? 

What happens when you touch the animal on its 
shell and at different places on its fleshy parts when it 
is feeding quietly ? 

Examine a mussel or clam which has been boiled, 
or hardened in alcohol. 

Press the valves together and quickly release them. 
Why do they fly open again ? 

When the mussel was alive what held the valves 
together ? Explain the manner of opening and closing 
the shell. 

Place the mussel on its side in a dish of water so that 
the dorsal portion is away from you. Is the anterior 
portion of the mussel near your right hand, or your left 
hand ? 

Carefully remove the upper valve without disturbing 
the soft parts beneath. Have you removed the right 
or left valve ? 

The membrane lining the interior of the shell is the 
mantle which secretes the material of which the shell 
is formed. Does this mantle line the entire shell ? Is 
it of equal thickness in all parts ? 

How many muscles held the valves together ? 

On a dry shell do you find the marks which show 
where the muscles were attached ? Do you find the 
muscles themselves ? 

Determine which is the posterior adductor muscle and 
which is the anterior adductor muscle. 

Find the mark which the mantle makes where it 
adheres to the inside of the shell. Call it the pallial 
line. Do you find any other markings on the inside of 
the shell ? Compare mantle outside of pallial line 
with that above. What is the relation of mantle to 
shell ? 

Raise the mantle and notice the striated leaf-like 
gills. How many do you find ? 

Look for the labial palps near the anterior portion 


MUSSELS AND SNAILS. 


157 


of the gills. How many do you find ? The mouth is 
between the palps. 

Examine the ventral and dorsal passages of the 
siphon. Are they connected ? Into what cavity does 
each lead ? 

See if you can find the heart near the dorsal margin. 

Have you found that the mussel has a head ? What 
organs of sense have you found ? 

Examine mussel-shells which have been burned for 
some hours in a hot fire. Compare with them some 



Fig. 123.—A Fresh-water Mussel ( Anodon ) Showing Position of Foot 
and Siphons. 

shells which have been immersed in weak acid for 
several days. Examine, also, oyster-shells which have 
been prepared in the same way. Describe the structure 
of a shell. 

On the dorsal margins of the valves of a shell find 








ANIMAL ACTIVITIES. 


158 

the hinge-teeth if there are any. How many teeth do 
you find on each shell ? 

Compare the shell of the common salt-water clam 
(My a Arenaria) with that of the mussel (CJnio). How 
do the teeth and hinge-ligament differ ? 

How do the markings on the inside of the shell differ ? 

What differences in the structure of the animals do 
these markings indicate ? 

In the same manner compare the shell of oysters, 
pectens, and other bivalves. 

Write a description of a shell you have not previously 
seen and compare your description with that given in 
Woodward’s Mollusca or a similar book. 

Summary of Drawings, (a) Sketch of a living 
mussel showing foot and siphons. 

(,b ) Cross-section of valves showing action of hinge. 

(c) Inside of shell showing all muscular impressions 
and the pallial line. 

(d) Sketch of mussel in its shell. 

(e) Cross-section of the body of the mussel near the 
umbo. 

(f) Shells of several bivalves. 

Activities of the Clam or Mussel. Feeding. We 

have already noticed currents of water flowing in and out 
of the siphon at the posterior end of the body. The 
water enters by the ventral opening and goes out by 
the dorsal opening. The dorsal and ventral passages 
are separated, and this separation continues through 
the body of the clam, dividing it into two chambers, 
the dorsal or cloacal chamber and the branchial or gill- 
chamber. In many marine clams the mantle-edges 
unite again below the branchial siphon, but in the 
fresh-water clam they are free along the ventral border. 
As water enters the lower siphon it brings with it food 
and oxygen into the branchial chamber. In this 
chamber hang the two pairs of ridged leaf-like gills 
bearing cilia which by their movements keep the cur¬ 
rents of water in motion. These cilia also select from 


MUSSELS AND SNAILS. 


159 


the water the minute animals and plants which nourish 
the clam. These bits of food are collected along the 
ridges on the gills and thence passed to their ventral 
edges, on each of which there is a groove leading to the 
mouth. Along this groove the food passes, whipped 
on by the cilia, until it enters the mouth, which is 



Fig. 124. —Fresh-water Mussel with One Valve Removed. p, peri¬ 
cardium; p.a., posterior adductor muscle; a.a., interior adductor 
muscle; a , anus; e.s ., exhalent siphon; i.s., inhalent siphon; l.m., 
cut edge of mantle; o.g., outer gill; v.g ., inner gill; /, foot; l.p., 
labial palps. 


situated between the labial palps at the anterior end of 
the body. 

To understand what becomes of the water that brings 
in the food we must remember that each gill is a fold 
of membrane pierced with tiny holes. In order to pass 
from the branchial chamber to the cloacal chamber the 
water must pass through these holes. A cross-section 
of a gill has a V shape, and the water goes through the 
sides of the V into the opening above and thence passes 
out of the cloacal chamber by the upper siphon. 






i6o 


ANIMAL ACTIVITIES. 


Nutrition. In the clam the various processes con¬ 
cerned in nutrition are more distinctly separated than 
in any of the other sub-kingdoms below the Arthrop- 
oda. When the food enters the mouth it passes down 
the throat to the stomach. The dark portion of the 
body surrounding this alimentary canal is the liver, 
which secretes digestive fluids and pours them on the 
food. The intestine beyond the stomach passes directly 



i 


Fig. 125. —Digestive Tube of Fresh-water Mussel ( Anodon'. in, mouth; 
l, liver; s, stomach; i and r, intestine; a, anus; p, pericardium; 
k, kidney; s.c., chamber above gills; g, gullet. 


through the heart and opens into the cloacal chamber 
in the current of water which passes out of the upper 
siphon. 

The digested food is taken up by the blood and 
carried to all parts of the body by the circulating 
system. The most important organ of .this circulating 
system is the heart, which is situated just below the 
hinge. It has a ventricle and two auricles. 

In its course, part of the blood is purified by the gills 




MUSSELS AND SNAILS. 


161 


and passes from these organs to the auricles. Part of 
the blood also flows through the renal organs, which 
take from the blood (excrete) the nitrogenous waste 
matters and empty them into the outgoing current of 
water. The ventricle forces the blood, constantly 
coming to the auricles, away from the heart all over 
the body. 

As in other animals, the separate cells take from the 
circulating liquid the substances necessary to produce 



Fig. 127.—Nervous System of Ano- 
don. c.g., ganglia near the mouth; 
p.g ., ganglia of the foot; o.g.> 
ganglia of the posterior adductor. 


Fig. 126.—Cross-section of 
Anodon. n, intestine; v.e., 
heart; i.g. and o.g., gills; 
/, foot; m ./., mantle. 


more cells like themselves or to manufacture intercel¬ 
lular structures. The cells of the mantle secrete 
carbonate of lime, which forms in layers on the inside 
of the shell and along its edges, thus increasing both 
its thickness and its size. If the mantle be irritated by 
the introduction of minute particles of foreign matter or 
by disease the secretion of carbonate of lime at a defi¬ 
nite point is hastened and a pearl is formed. 

Respiration. As the water passes through the gills 
it flows over and around many blood-vessels, through 






162 


ANIMAL ACTIVITIES. 


whose walls the interchange of gases common in all 
breathing takes place. 

Reproduction. The eggs of the fresh-water mussel 
pass from the ovaries to the cavity of the outer gill, 
where they hatch. The number of young is enor¬ 
mous. They remain for a time within these gills and 
then pass out to grow or to be destroyed, as the case 
may be. 

Discovery. The senses of the mussel are not acute 
and there are no special organs of sense. Touch is 
more acute in the foot and at the margins of the 
mantles, as might be expected, these being almost the 
only exposed parts. There is a so-called ear-sac in 
the foot, but it is not probable that the mussel can hear. 

The nervous system consists of three pairs of ganglia 
connected by nerves. One pair form a sort of brain 
{the snpraoesophageal ganglia ), one pair lie directly 
under the posterior adductor muscle {the visceral 
ganglia ), and the third pair are imbedded in the tissue 
where the foot joins the body {pedal ganglia). 

Motion. The opening and closing of the shell at 
will is brought about by the action of an elastic hinge- 
ligament and a pair of adductor muscles. When the 
muscles contract the shell is closed; when they relax 
the hinge-ligament acts like a door-spring and forces 
the valves apart. 

The foot is protracted partly by muscular activity 
.and partly by increasing its size by pumping its vascular 
vessels full of blood. When left lying on its side in 
the aquarium the animal rises to an erect position by 
sinking its foot into the sand. It plows its way through 
the mud or sand by muscular contractions of this foot. 

The Garden-slug. Obtain some garden-slugs, or, 
better still, some of the larger slugs found in damp 
cellars or green-houses. Keep them in a box with 
plenty of moisture and feed them with cabbage-leaves 
and bread. Watch the mode of locomotion. Allow 
the animal to crawl on a piece of glass and watch the 


MUSSELS AND SNAILS . 163 

movements of the foot. Examine the trail of mucus 
left as the animal advances. 

Do you find the place from which this mucus comes? 
Do you find a head ? a neck ? 

What organs of sense do you find ? Describe their 
position. 

How does the slug feed ? Has it a shell ? a mantle? 
On which side of the body is the breathing orifice ? 
How often does the slug breathe ? 

How often do you breathe ? 

Is there any relation between rapidity of breathing 
and rapidity of movement ? 

Do you call the slug’s body warm or cold ? 



Fig. 128.—A Slug. 


Does the rate of breathing have anything to do with 
the snail’s temperature ? 

Write resemblances and differences for slug and fresh¬ 
water mussel. 

Sketch the slug as you see him. 

Pond-snails. These animals are found in almost 
all ponds, crawling on dead leaves or aquatic plants. 
They may be easily kept in a jar of water for class- 
study. Get some pond-snails and keep them in a jar 
of fresh water. Watch all their movements. 

Write resemblances and differences for snail and 
slug. Note all points mentioned in regard to slug and 
mussel. 





164 


ANIMAL ACTIVITIES. 


Can a snail leave its shell and return ? 

Can it close its shell ? 

Examine different kinds of snails for this charac¬ 
teristic. 

Do all the snails you have seen breathe in the same 
way ? 

Can a snail swim ? 

Can it walk on the surface of the water ? 

Is the snail bilateral ? 

Compare a land-snail with a water-snail. 

Study several shells and notice the sutures, the 
apex, the spire, the whorls, the lines of growth, the 
aperture, and the lip. Compare these parts in snail- 
shells of different kinds. 

Notice all other differences and tabulate your obser¬ 
vations. The columella is the axis of the spire. The 
piece which closes the snail’s shell is the operculum. 

Hold the shell with the apex upward. Is the aper¬ 
ture toward the right ( dextral ) or the left (sinistral ) of 
the columella ? 

Is the aperture notched or entire ? 

Describe a shell from observation of the specimen 
and compare your description with that found in a 
standard work. 

Summary of Drawings, (a) A pond-snail as it 
appears while crawling X 3- 

(h) A shell of litorina or similar shell. 

(c) A shell of purpura or a similar shell. 

(< d) A shell of a limpet. 

(e) Right valve of an oyster. 

if) Various shells showing different structures. 

Snail and Mussel. A comparison of the snail and 
mussel shows on the part of the snail a distinct advance 
in the collecting of organs of sense at the anterior por¬ 
tion of the body and the growth of a head there. The 
possession of a head with a brain and active sense- 
organs is apparently associated with the matter of food- 
supply and feeding. So long as a soft-bodied animal 


MUSSELS AND SNAILS. 


165 

can have all the food he wishes brought to him by 
currents of water there is no use for head, or eyes, or 
sensitive feelers. O11 the other hand, an animal which 
must forage for his food can do it more advantageously 
if he learns to walk head foremost. In order to make 
great progress in this way he must have some means 
of discovering obstacles in his pathway. Hence the 
necessity of feelers and eyes. In the struggle for food 
among animals the headward growth, and specialization 
is a great advantage. 

Active exercise in earning a living in competition 
with other animals which desire the same food not only 



Fig. 129.—A Snail. 

sharpens the wits but actually increases the physical 
development of those organs on whose activity intelli¬ 
gence depends, just as vigorous muscular exercise 
develops the parts trained. 

Mussels and snails belong to the sub-kingdom Mol- 
lusca. The mussels, clams, oysters, and similar 
bivalves are members of the class Pelecypoda. These 
animals are sometimes called Lamellibranchiata be¬ 
cause they have four leaf-like gills, and sometimes 
Acephala because they have no heads. 

Univalves like the snails and the limpets, and slugs 
which have no shells, are classed as Gastropoda. 





166 


ANIMAL ACTIVITIES. 


Another important class of mollusks is the Cephalop¬ 
oda. The squid belongs to this class, as do the 
octopus, the argonaut, and the 
pearly nautilus. 

Characteristics of Mollusca. 
The name Mollusca is given 
on account of the fact that the 
bodies of these animals, ex¬ 
cepting the shell, have no hard 
parts. In Mollusca the body 
is typically bilateral. There is 
a mantle present which in most 
cases secretes a shell which is 
as much a part of the animal 
as is the mantle itself. These 
shells increase in size as the 
animal grows, and so exhibit 
lines of growth. A fleshy foot 
is also present. The nervous 
system consists of three pairs of ganglia connected by 
nerves. Eyes are present in many forms and in the 
higher cephalopods they closely re¬ 
semble the eyes of Vertebrates. In 
all but the Pelecypoda the mouth is 
provided with a lingual ribbon, which 
is a sort of rasp in the mouth by 
which in many cases thick shells may 
be bored entirely through. 

Questions. How do the sense- 
organs of mollusks which forage for 
food compare with those of sedentary 
mollusks ? 

What protective devices do you 
observe among mollusks ? 

How can one compel an oyster to 
produce a pearl ? 

Topics for Reports. Tyrian Dyes. Eye-stones. 
The Octopus and Squid. The Chambered Nautilus. 



Fig. i3i.—P art of 
a Lingual Rib¬ 
bon ( magnified ). 



Fig. 130.—A Squid. P, 
its pen. 







MUSSELS AND SNAILS. 


167 


The Argonaut. Some Fabulous Monsters of the Sea. 
Oyster Farming. Pearl Fisheries. Famous Pearls. 
The Ship-worm. Wampum and Suckanhock. The 
Scallop. 

VOCABULARY. 


Ad duc'tor (Lat. ad , to, and duco, 
lead), a word applied to the 
muscles which hold together the 
shells of bivalves. 

An'o don (Gr. a, priv., and -odous, a 
tooth), a genus of fresh-water 
mussels having no hinge-teeth. 

Bi'valve (Lat. bi, two, and valva , 
a leaf of a door), having two 
shells which open and shut. 

Bran'chia (Gr. branchia, gills, pi. 
of branchion, a fin), gills. 

Bys'sus (Gr. byssos , a kind of flax), 
a bunch of tough threads by 
means of which some bivalves 
attach themselves to rocks. 

Carniv'orous (Lat. caro , flesh, 
and voro , to devour), flesh-eat- 
ing. 

Columel'la (Lat. dim. of colu¬ 
men, a column), the upright pil¬ 
lar in the axis of a univalve shell. 

Dex'tral (Lat. dexter , right), 

right-handed, 

Epider'mis (Gr. epi , upon, and 
derma , skin), the outer skin of an 
animal. 

Her biv'o rous (Lat. herba , grass, 
and voro , to devour), vegetable¬ 
eating. 

Hinge Lig'ament (Lat. ligo, to 
bind), an elastic substance forc¬ 
ing open bivalve shells when the 
muscles relax. 

Lin'gual Rib'bon (Lat. lingua , 
tongue), a rasp-like organ used 
in boring holes through shells. 

Man tie (Lat. manus , hand, and 


tela , a web), the soft outer cover¬ 
ing of the body of a mullusk, 
commonly just under the shell. 

Na'cre, mother of pearl. 

(E soph'a gus (Gr. oiso , will bear 
and phagein , to eat), the tube 
leading from the mouth to the 
stomach. 

0 per'cu lum (Lat. operculum , a 
lid), the lid closing the aperture 
of a snail’s shell. 

Pal'lialLine (Lat. pallium, a man¬ 
tle), the mark on the inside of a 
mollusk-shell made by the man¬ 
tle. 

Se'tae (Lat. pi. of seta , a bristle), 
bristles. 

Sin'is tral (Lat. sinister, left), left- 
handed. 

Si'phon (Gr. siphon, a siphon), a 
tube for passing water through 
the gill-cavity of* a mollusk. 

Su'pra ce soph a ge'al (Lat. supra , 
above, and oesophagus ), an ad¬ 
jective applied to the ganglion 
above the throat. 

Umbil'icus (Lat. umbilicus , 
navel), an opening near the cen¬ 
tre of the base of some spiral 
shells. 

Um'bo (Lat. umbo, the boss of a 
shield), a prominence near the 
hinge of a bivalve shell. 

Un'io (Lat. unus, one), a genus of 
fresh-water mussels. 

Whorl, one turn of the spire of a 
univalve shell. 



ANIMAL ACTIVITIES, 


168 


<u 

a 

a 

o 

tn 

m 

rt 


o 


Earthworm. 







Clam. 







Starfish. 







Hydra. 



* 




Sponge. 

* 







as 

•O 

8 

a 

< 


n-. 

xi 

d 

<u 

— rt 

2 £ 

4> 5 


PG 


(/> 


flj 

cu 

aj 

id 

C/2 


ll • 

O X 
<D 

in Si 

ta o 

d — 

■r crj 

^ d 

Si 


co 

£ c 

J ^ 

dn 


d~ 

o 

jy 

13 

C /2 


(/) 

JU . 

d rt 
o d 

d* o3 
10 -*_. 


d 

o 

-*-* 

o 

£ 

o 

CJ 

o 


<u 

o 


b/> 

d 


cj 

<U 

Si 

X> 

u 

& 

(/) 

a 

d 

to 

u 

o 


c/i 


G 

<D 

to 

VH 


o 


(/) 

G 

oj 

b/) 

o 




























































CHAPTER XVI. 


THE STRUCTURE AND ACTIVITIES OF A FISH. 

Goldfish or other small fish from streams or 
ponds are easily kept in aquaria. With a few living 
fish placed where pupils can observe them, and a 
smelt or perch from the market as an individual 
specimen for study on each bench, the following ques¬ 
tions may be answered: 

Shape and Covering. Is the fish bilateral ? Esti¬ 
mate length, thickness, and depth. 

What is the shape of the body ? 

Do you find a head ? a neck ? 

Do you find scales ? Do they cover the entire 
animal ? 

Are the scales joined edge to edge ( tesselated ) or 
do they overlap {imbricated)? 

Remove some of the skin. What is the appearance 
of the muscle below ? 

Notice the line extending along the side of the fish 
from head to tail {lateral line). Do the scales cover¬ 
ing this line differ from those found elsewhere on the 
body ? 

The Fins. How many fins do you find ? How 
many are dorsal ? How many ventral ? How many 
are paired ? 

Which fins correspond to the limbs on our own 
bodies ? 

The paired fins nearest the head of the perch are 
called the pectoral fins, those somewhat farther back 
nearer the anal opening are called the pelvic fins. The 
large fin along the back is the dorsal fin. The unpaired 

169 


ANIMAL ACTIVITIES. 


170 

fin along the median ventral line is the anal or ventral 
fin. The fin at the end of the tail is the caudal fin. 
Sketch a fish with fins extended. Indicate the names 
of the fins. 

Of what use are the bones in the fins (fin-rays)? 

Does the fish swim by using its fins, or its tail, or 
both ? 

The Head. What organs of sense do you find ? 
The ears are internal. 

Are the eyes movable ? Do they have lids ? How 
does the eye of the fish resemble the eye of man ? of 
the grasshopper ? How does it differ from these ? 

Do the nostrils open into the mouth ? Use a tooth¬ 
pick for a probe. Are the nostrils of use in breathing ? 
Of what use are they ? 

Does the mouth open vertically, or laterally ? Where 
are the teeth situated ? What is their shape ? What 
about the shape and position of the tongue ? 

Gills and Heart. What movements does the fish 
make while breathing ? 

Raise the gill-cover of the specimen on the bench. 
Tow many gills do you find ? How many gill-clefts 
:>r spaces between the gills ? 

The bony supports of the gills are called branchial 
arches. The soft delicate red branches from these 
arches are the gill-filaments. In these the blood is 
purified. What is the color of the blood of a fish ? 
Can you see the branchial arches by looking into the 
mouth of a fish ? 

Remove the skin and muscular walls from that por¬ 
tion of the ventral cavity directly behind the gills. 
T his exposes the heart. Can you see the swellings 
indicating the two cavities of the heart, the auricle and 
the ventricle ? The ventricle has the form of a tri¬ 
angular pyramid. The auricle is thin-walled and filled 
with venous blood, hence it looks like a clot of blood 
attached to the ventricle. The large blood-vessel 
from the heart to the gills is the ventral aorta. Its 


THE STRUCTURE AND ACTIVITIES OF A FISH . 171 


enlargement near the heart is called the arterial bulb. 
The blood-vessels 
bringing blood to the 
heart are called veins. 

Do you find the ventral 
aorta, the arterial bulb, 
and a large vein ? Make 
a sketch to show their 
position. 

Sketch a single gill 
from a cod, or other 
large fish. Indicate the 
parts observed. Trace 
the course of the blood¬ 
vessels in an injected 
specimen. 

Internal Structure. 

With a sharp knife 
make a cross-section 
of the body of a fish a 
little in front of the 
anal opening. Sketch 
the appearance of the 
section, showing the 
location of the vertebral 
column or back-bone, 
the spinal nerve within 
the neural cavity, the 
visceral cavity, and the 
muscles surrounding 
all. Do you find any 
large blood-vessels ? 

Place the fish on 
its side in the bottom 
of a pan containing 
water enough to cover 
it. With scissors re¬ 
move the portion covering one side of the digestive 



Fig. 132.— The Circulation of Blood in 
a Fish. A , aortic bulb; Z/, heart; B , 
arteries supplying gills; V\ veins; b, 
veins conveying aerated blood from 
the gills to the dorsal aorta; Z, vessels 
of liver; A\ kidney. 





172 


ANIMAL ACTIVITIES. 


cavity, being careful not to disturb the organs within. 
Do you find the body-cavity ? 

Pass a probe down the mouth until you are able to 
make out the stomach, the oesophagus, extending from 
the mouth to the stomach, and the intestine, extending 
from the stomach to the anal opening. This is the 
alimentary canal. Is the intestine coiled or straight ? 
Sketch this alimentary canal. 

Do you find a membrane holding the stomach and 
intestine in place ? This is the mesentery. Do you 
see blood-vessels in the mesentery ? 

In the front of the body-cavity do you see the large, 



Fig. 133.—Internal Organs of Fish, a , oesophagus; bed , stomach; /, 
duct of swimming-bladder; k , swimming-bladder; h , ovary. 


brownish liver ? Can you find a gall-bladder, green 
or yellow in color, attached to the liver ? 

In the body-cavity can you see the reproductive or¬ 
gans ? Usually these are smooth and whitish in the 
male and yellow and granular in the female. 

Directly under the back-bone do you find the air- 
bladder ? This organ is homologous with the lungs of 
higher vertebrates. Do you also find a large blood¬ 
vessel above the air-bladder ? 

Brain and Nerves. Use the head of a large fish 
obtained from the market. With great care remove 
the upper part of the skull. Commonly it is better to 
use preparations previously dissected by the teacher. 
These may be kept in formalin, or alcohol. The 



THE STRUCTURE AND ACTIVITIES OF A FISH . i ?3 


largest pair of globular masses are the optic lobes. In 
front of these we find the cerebral lobes, corresponding 
to the cerebrum or front brain in man. Behind the 
optic lobes the cerebellum is situated. Sketch the brain 
showing all these parts, showing also the olfactory 
nerves extending to the nostrils, the optic nerves lead¬ 
ing to the eyes, the auditory nerves leading to the 
ear-sac with its “ear-stone,” and the spinal nerve 
extending along the back. 

The Bones of a Fish. Skeletons or parts of skele¬ 
tons can be easily prepared for laboratory use by soak¬ 
ing in hot water. Heads and backbones of large fish 
can be obtained without cost at the markets in most 
places. 



Fig. 134.—Skeleton of a Fish. 


With the skeleton of a fish notice the visceral cavity 
and the neural cavity. What is the relation of these 
cavities ? 

Notice the brain-cavity. Where was the brain con¬ 
nected with the spinal cord ? 

Do you find openings for nerves extending to ears, 
eyes, and nostrils ? 

Do you see how the skull is joined to the vertebral 
column ? 


i74 


ANIMAL ACTIVITIES, 


How is the lower jaw suspended from the skull ? 

Separate the back-bone, or vertebral column, into 
parts (vertebrae). Are the vertebrae near the tail like 
those near the head ? Study particularly one of the 
vertebrae near the tail. The main part of a vertebra 
is the centrum. Is the centrum entirely solid ? What 
is its shape in a longitudinal section after removing all 
soft parts ? Sketch front and side view of a vertebra, 
and a longitudinal section. 

Do you find the cavity for the spinal cord ? Call 
this cavity the neural cavity, and the processes at¬ 
tached to the centrum and enclosing the neural cavity, 
the neural arch, and the spine above it the neural 
spine. Is this spine dorsal or ventral ? Does it 
point towards the anterior or the posterior part of the 
body ? 

Do you find the cavity for the passage of the large 
blood-vessel ? Call this the haemal arch, and the spine 
attached to it the haemal spine. This arch protects 
the dorsal aorta. Are there any ribs present ? 

Using one of the vertebrae above the visceral cavity, 
find how it differs from a vertebra near the tail. 

Summary of Drawings. ( a ) Side view of fish with 
fins extended. 

( b ) Side view of head of a fish showing as many parts 
as possible. 

(< c ) Gill of a fish showing parts. Heart of fish with 
arteries and veins. 

( d ) Cross-section of the body of a fish a little in front 
of the anal opening. Sketch of alimentary canal. 

(<?) Brain of fish with nerves. 

(/) End view of a vertebra from near the tail. 

(g) End view of a vertebra above the visceral cavity. 

(h) Longitudinal section of a vertebra. 

Vertebrates. The study of a fish introduces us to 

the class Vertebrata of the sub-kingdom Chordata. 
The possession of a back-bone made up of vertebrae 
gives this class its name. This back-bone furnishes a 


THE STRUCTURE AND ACTIVITIES OF A FISH. 175 


flexible axis for the body, and separates the neural 
from the visceral cavities. 

In the young of all vertebrates a rod of cartilage 
called the notochord runs through the body between 
the two cavities just mentioned. In some of the lower 
vertebrates this rod persists throughout life, but in nearly 
all cases it disappears with the hardening of the centra 
of the vertebrae. The soft substance extending through 
the centra of the vertebrae of the fish probably repre¬ 
sents in that animal the remnant of a notochord. In 
all adult vertebrates higher than fishes there is left no 
trace of this structure. 

The neural cavity, as its name implies, contains the 
main nerve of the body, the spinal cord. This cord is 
enlarged at its anterior end in almost all vertebrates, 
forming a brain. In all higher vertebrates and in by 
far the greater part of those lower in organization, this 
brain is enclosed in a bony box called the skull. 
Paired organs of sense are connected with the brain. 
The visceral cavity contains the organs of digestion, 
the heart, and organs of reproduction. In higher 
vertebrates it also contains the lungs. 

In the great majority of vertebrates there are two 
pairs of limbs. These are, in the higher vertebrates, 
usually attached to the main axis of the body by con¬ 
necting bones called respectively the pectoral girdle 
and the pelvic girdle. Even in vertebrates which have 
no arms or legs rudiments of these girdles may some¬ 
times be found. 

Fishes. The fishes (Pisces) include animals which 
live in water and breathe by gills. The body is usually 
covered with scales, and the form is adapted for loco¬ 
motion through the water. The paired fins are chiefly 
used for balancing the body, and the caudal fin is the 
principal organ of locomotion. Although nasal sacs 
and nostrils are present, they do not connect with the 
mouth or throat. There are no external ears. In 
most fishes an air-bladder is present, often connecting 


176 


ANIMAL ACTIVITIES. 


with the gullet. This bladder serves to vary the 
specific gravity of the fish in the water. Sometimes it 
is used in producing a noise. It is homologous with 
the lungs of higher vertebrates. 

The heart in fishes consists of one ventricle and one 
auricle. Impure blood, collected by the veins, gathers 
in the auricle and passes to the ventricle, whence it is 
forced through the gills where the ordinary interchange 
of gases takes place. The blood is then distributed to 
all parts of the body by arteries. See Fig. 132. 

Questions. What do you mean by saying that a fish 
is cold-blooded ? 

How much can a fish see ? 

How much can it hear ? 

What is meant by saying that a fish’s ears are 
probably organs of equilibrium ? 

Where are organs of equilibrium situated in some 
other animals ? 

How does the tail of a shark differ from that of a 
salmon ? 

How do the skeletons of the two animals differ ? 

Topics for Reports. The Nests of the Stickleback. 
The Migrations of Salmon. Bream. Trout. Sharks. 
Electric Eels. The Sea-serpent. Flying Fish. 


VOCABULARY. 


A or'ta (Gr. aeiro , to raise), the 
large artery of the body. 

Ar'te ry (Gr. arteria , windpipe), 
a tube carrying blood away 
from the heart. 

Cau'dal (Lat. cauda, tail), pertain¬ 
ing to a tail. 

Cen'trum (Lat. centrum , a centre), 
the body of a vertebra. 

Cerebel'lum (Lat. dim. of cere¬ 
brum ), the hind brain. It con¬ 
trols combined muscular action. 

Cer'e brum (Lat. cerebrum, brain), 
the front brain, the seat of the 
reasoning faculties. 


Chor da'ta (Gr. chorde , a chord). 
The sub-kingdom including the 
back-boned animals. 

Hae'mal (Gr. haima , blood), per¬ 
taining to the blood. Sometimes 
used with the same meaning as 
visceral. 

Het er 0 cer'cal (Gr. heteros , differ¬ 
ent, and kerkos , tail), applied to 
the tails of fishes having unequal 
lobes. 

Ho mo cer'cal (Gr. homos , same, 
and kerkos'), a word applied to 
the tails of fishes having equal 
lobes. 



THE STRUCTURE AND ACTIVITIES OF A FISH. 177 


Im'bri ca ted (Lat. imbrex , gutter- 
tile), overlapping. 

Max'il la ry (Lat. macero, to soft¬ 
en), pertaining to the jaw; com¬ 
monly to the upper jaw. 

Mes'en te ry (Gr. mesos , middle, 
and enteron, intestine), in verte¬ 
brates the membrane holding 
the intestines in place. 

Neu'ral (Gr. neuron , a nerve), per¬ 
taining to the nerves. In verte¬ 
brates it is applied to the dorsal 
cavity of the body. 

No to chord (Gr. not os, back, and 
chorde , a cord), a rod of carti¬ 
lage from which the vertebral 
column develops in vertebrates. 

<E soph'a gus (Gr. oisd } will carry, 


and phagein , to eat), the tube 
connecting the throat with the 
stomach. 

0 per'cu lum (Lat. operculum , a 
lid), the gill-cover in fishes. 

Pec'to ral (Lat. pectus , breast), 
pertaining to the breast. 

Tes'sel la ted (Lat. tessellatus , 
checkered), formed in squares 
like mosaic. 

Ver'te bra (Lat. verto , to turn), 
one of the sections of the verte¬ 
bral column. 

Vis'ce ral (Lat. viscera , internal 
organs of the bodyi, pertaining 
to the internal organs; applied 
to the ventral cavity in verte¬ 
brates. 



For Note-book. 


178 


ANIMAL ACTIVITIES. 


•d 

CO 







u~ 







Grass¬ 

hopper. 







Earth¬ 

worm. 







3 














u 







Starfish. 







Hydra. 



• 




Sponge. 







Amoeba. 








Feeding. 

Nutrition. 

Respiration. 

Reproduction. 

Discovery. 

Movements. 






































































CHAPTER XVII. 


TADPOLES AND FROGS. 

In the study of the frog, aquaria are indispensable. 
The expense, however, need not be large. In one 
aquarium tadpoles should be placed together with a few 
aquatic plants. The minute green plants which grow 
on the sides of the aquarium will furnish food enough. 
The adult frogs can be kept in a box with glass sides 
with only a small amount of water in the bottom and 
a netting to cover the top. In warm weather frogs 
feed on insects; in winter they go without food. 

The Tadpole. Is it bilateral ? 

Is the skin naked or scaly ? Do you see a lateral 
line ? 

In what ways does it resemble a fish ? 

How does the tail of a tadpole differ from the tail of 
a fish ? 

In any of the tadpoles can you see the beginnings of 
limbs ? Which limbs appear first ? 

In a young tadpole how do the gills appear ? 

Can you see the gills in an older tadpole ? Do tad¬ 
poles come to the surface of the water to breathe ? 

Can you find in a specimen which has been hardened 
in alcohol a gill-cavity ? Can you find an opening into 
this cavity ? 

Are the jaws hard or soft ? Watch the tadpoles 
feeding on the sides of the aquarium, or jar. 

How does the size of the mouth compare with that in 
the adult ? 


i79 


i8o 


ANIMAL ACTIVITIES. 


In a specimen which has been hardened in alcohol 
do you find vertebrae ? Do you find a notochord ? Do 
you find muscles like those in the fish ? Notice the 
spirally coiled intestine. 

Hold the tail of a living tadpole under a compound 
microscope and observe the movement of the blood. 
Notice the corpuscles. 

Summary of Drawings. ( a ) Side view of tadpole. 

( b ) Dorsal view of a young tadpole to show gills. 

(c) Sketch to show blood-vessels as seen under the 
microscope. 

The Frog Alive. How does the frog resemble the 
fish ? the tadpole ? 

Do you find scales, hair, claws, or nails ? 

Do you find tail or fins ? How about legs ? 

What is the frog’s mode of locomotion on land ? in 
water ? 

How many divisions have the hind limbs ? the fore 
limbs ? How do they compare with the limbs of the 
human body ? Do the joints move in the same way as 
ours ? Do you find arm, forearm, and wrist ? 

How many fingers ? How many toes ? Are fingers 
or toes webbed ? Do you find a thumb ? 

How does the frog take its food ? How does the 
tongue act ? 

What movements are made in breathing ? Are 
there any gills ? How long can a frog live under 
water ? 

Does the frog have the same senses and the same 
organs of sense as man ? 

Do you find ears ? eyelids ? Do you find a mem¬ 
brane covering the eye (nictitating membrane) ? 

Frog Hardened in Alcohol. Look in the mouth. 
Do you find any teeth ? How many ? Where are 
they ? 

What is the shape of the tongue ? 

Do the nostrils connect with the mouth ? 

. Does the ear-cavity connect with the mouth ? 


TADPOLES AND FROGS. 


181 

(Eustachian tube.) Cut open the membrane covering 
the ear and use a probe. 

Using a prepared specimen showing the internal 
organs, do you find the peritoneum ? the mesentery ? 
the stomach ? the intestine ? the liver ? the heart ? 

Do you find the lungs ? 

Is there a diaphragm separating the heart and lungs 
from the stomach, liver, and intestine ? 

Dorsal to the viscera in a freshly prepared specimen 
look for nerves branching out from the spinal cord. 
Do you find nerve-masses (ganglia) on these nerves on 
each side of the spinal column ? Are these ganglia 
connected by a nerve running lengthwise ? Call this 
the sympathetic system of nerves. 

In a prepared specimen notice the brain and spinal 
cord. Sketch the brain in outline. How does this 
sketch compare with the sketch you have made of the 
brain of the fish ? 

In what ways does a frog resemble a fish ? How 
does the frog differ from the fish ? 

Summary of Drawings, (a) Outline of organs seen 
in the visceral cavity. 

(^) Sketch of ganglia of sympathetic system with 
connecting nerves. 

(c) Outline sketch of brain of frog. 

Activities. Both the structure and the activities of 
the frog interest us because they are so much like those 
of man himself. The frog has been much studied 
because of the remarkable changes in structure and 
habits which the animal undergoes after leaving the 
egg- 

Taking Food. The frog lives on insects, worms, 
and other small animals. As a rule frogs eat only dur¬ 
ing the summer months, remaining torpid without food 
in winter. The tongue of the frog is peculiarly adapted 
for catching insects. It is fastened to the lower jaw 
by its front end, and turns a somersault when shot out 
at a fly. The hinder end is covered with a sticky 


182 ANIMAL ACTIVITIES. 

saliva which holds the fly a prisoner until the jaws 
close over him. The ease and quickness with which 

an insect disappears are 
always a surprise to the 
observer. 

When feeding on large 
animals the frog seizes his 
prey with jaws and front 
legs, and hurriedly crowd¬ 
ing his luckless victim into 
his mouth, swallows him 
alive. Teeth are present 
on the upper jaw and on the 
palate or roof of the mouth. 

Taking Oxygen. When the young frog emerges 
from the egg it takes air from the water by means of 
external gills. Into these the blood is pumped directly 
from the heart, as in fishes. Here the oxygen passes „ 
into the blood for purification, and thence is conveyed 
to all parts of the body. 

In a few days these external gills disappear, and 
other gills grow under the opercular membrane. This 



Fig. 135.—Tongue of a Frog. 



Fig. 136.—A Young Tadpole Showing External Gills. 


membrane is joined to the body-wall except on the left 
side, where an opening for the passage of water remains. 
The young frog now breathes like a fish. The 





TADPOLES AND FROGS. 183 

heart, too, like that of a fish, has only two chambers, 
an auricle and a ventricle. 

After a time lungs develop, and the tadpole, while 
still using his gills to some extent, finds it necessary 
to come to the surface of the water occasionally for air. 
Finally the gills disappear and the frog breathes only 



Fig. 137.—Under Side of Tadpole Showing Coiled Intestine and Internal 

Gills. 


by lungs. While these changes are going on, the 
heart develops another auricle on the left side for the 
reception of the purified blood from the lungs. The 
right auricle receives the impure blood returning from 
the circuit of the body. 

Not only does the frog, at different times, breathe in 
the three ways just mentioned, but at all times it 



Fig. 138. — Heart of 
Adult Frog. a, 
auricles ; v, ven¬ 
tricle. 



Fig. 139. — Blood-cells 
of a Frog, a , red cor¬ 
puscle; b, colorless cor¬ 
puscle. 


breathes by the entire surface of the body, the skin 
being especially rich in blood-vessels. 








184 


ANIMAL ACTIVITIES. 


The adult frog pumps the air into the lungs by the 
movements of the muscles of the throat and lower part 
of the mouth-cavity. When the mouth-cavity enlarges, 
air rushes in through the nostrils. When the cavity 
contracts, valves close the openings to the nostrils and 
the air is forced down into the lungs. The frog has 



Fig. 140.—Blood-corpuscles of Man. s, A, r ", red corpuscles ; p and 
g, white corpuscles; c , crystals. 

neither ribs nor diaphragm—organs of great importance 
in our own breathing. 

The oxygen, once taken by the blood, is carried by 
the red corpuscles, or blood-cells, to all parts of the 
body, where in the capillaries it is given up to burn, 
or oxidize, tissues and food substances in order to 
produce heat and energy. 

Nutrition. Food passes from the mouth to the 
stomach, where it is acted on by fluids like those in our 
own bodies. It then passes to the intestines, where 
the bile secreted by the large liver and the pancreatic 


TADPOLES AND FROGS. 


185 

juice from the pancreas are poured upon it. Here 
further changes take place and the digested food is 
absorbed and taken to the blood-vessels. The un¬ 
digested portions of the food pass along the intestine 
to the cloaca , which is the common receptacle for use- 



Fig. 141.—Viscera of Frog. Sm./n., small intestine; Z. 7 ., large intes¬ 
tine; Ur.BL, bladder; pe.ca ., pericardial cavity; V, ventricle; T.A., 
large artery; Ao , aorta; /, pulmonary artery; Fn, pancreas. 

less substances from the food-tube, and the kidneys 
and eggs or sperm-cells from the reproductive organs. 
Thence the useless matter and the reproductive cells 
pass from the body. 

When the tadpole first comes from the egg, the food- 
tube quickly grows into the long coiled tube shown 
in Fig. 137 and this in turn gives place to the tube as 
we have seen it in the adult frog. 

It is interesting to note that the lungs, liver, and 
pancreas are outgrowths from the side of the food-tube, 







ANIMAL ACTIVITIES. 


186 

produced by a pushing out of the walls of the tube 
itself (Fig. 143). 

Excretion. Carbon dioxide and water are taken by 
the blood-corpuscles to the breathing organs and to the 
skin, where they are thrown out of the body. Urea and 



SMALL 

INTESTINE 


STOMACH 


LARGE 

INTESTINE 


12 INCH 
DUODENUM 


Fig. 142.—Digestive Organs of Man. 

water are taken from the blood by the kidneys and 
passed along to the urinary bladder and thence out ol 
the body. 

Reproduction and Metamorphosis. The female 
frog deposits her eggs in the water in spring in large 
jelly-like masses. As soon as hatched the young tad- 


TADPOLES AND FROGS. 


187 


poles cling - in clusters to plants, or other objects; life 
being sustained by the food-yolk within the body. 
After a few days, a mouth with horny jaws develops 
and the animals begin to feed. 

The tadpole now eats plants, being especially fond 
of the green confervae so common on the sides of 
aquaria. 

Growth is now rapid, and in a few months the legs 
appear and the tail is absorbed. 



Movements. The most important organs of motion 
are the muscles. A muscle causes movement by 
shortening itself, and thus bringing nearer together its 
two ends with whatever is attached to them. In gen¬ 
eral, muscles are attached to bones. How muscle and 
bone together produce movement may be well under¬ 
stood by studying Fig. 148 in connection with the 
movements of the human arm. 





i88 


ANIMAL ACTIVITIES. 


A muscle shortens because the cells of protoplasm 
of which it is composed all have the power of contrac¬ 


tility. The cells 
all contract in one 



D | V*# V*.y direction, making 

^ the whole muscle 

Fig. 144.— Growth of Frog’s Egg. shorter and thicker. 

These contractions 


are under the control of the nerves. 

A number of muscle-cells make one of the fibrillae. 
Several of these fibrillar wrapped in a sheath form a 
fibre. The fibres are wrapped in bundles, and these 
bundles are covered by a thin layer of tough connective 
tissue. The sheaths or coverings of muscles, bundles, 
and fibres unite to form tendons by which the muscles 
are attached to the bones (Figs. 149 and 150). 

Muscles under the control of the will, like those in 
the leg of a frog or of a man, show peculiar cross-mark¬ 
ings. Muscles not under the control of the will, like 
those of the intestine or stomach, 
are commonly unstriped. 



The bony skeleton of the frog, 
on which the muscles act to cause 
the movements of the body, has 
an axis of nine movable bones, 
the vertebrae. Behind these a 
long bone, the urostyle, reaches 
to the hips, and in front is at¬ 
tached the head with its broad 
skull and large jaws. On the 
base of the skull are two rounded 


prominences called condyles, fig. 145.—Very Young 
which fit into corresponding de- Tadpoles, 

pressions on the atlas-bone, the 
first bone of the vertebral axis (Fig. 15 1). 

The fore limbs are attached to the axial skeleton by 
muscles and ligaments. A shoulder, or pectoral girdle, 
consisting of several bones is present. The hinder 



TADPOLES AND FROGS. 


189 


limbs are attached to the axial skeleton through the 
pelvic girdle. The bones of the arm consist of the 
humerus , or forearm, the radio-ulna , corresponding to 



Fig. 146.—Various Stages of Tadpole. 


the two bones, the radius and idna in man, the carpal 
or wrist-bones, the metacarpal or hand-bones, and the 
fingers or phalanges. In the leg are the femur or 
thigh-bone, the shin-bone corresponding to the tibia 




Fig. 147.—Young Frogs. 


and fibida in man, the tarsal bones, two of which are 
much longer than the others, the metatarsal or ankle- 
bones and the phalanges (Fig. I 5 2 )- 

Controlling the organs of motion and extending into 



190 


ANIMAL ACTIVITIES. 


every muscle for that purpose is the nervous system. 
This consists of a brain connected with the spinal cord, 
and a series of ganglia with nerve connections - in the 
visceral cavity. From these centres nerves run to all 
parts of the body. The division between brain and spinal 
cord is not so sharp as in man. The brain itself has the 
same parts as the brain of man, but these parts do not 
have the same shape or relative size (Figs. 15 3 and 154). 



Fig. 148.—The Use of a Muscle. 


Notice how large the olfactory and optic lobes appear 
in the frog. In man they are small and do not show 
in the figure. In man, too, the cerebrum or forebrain 
has grown so large that it occupies almost the whole 
of the brain-cavity. These facts of structure would 
seem to indicate that sight and smell are of more im¬ 
portance to the frog than memory or reason. 

Discovery. It is the duty of the nervous system to 
keep in touch with the outer world, in order that the 
movements made may be useful to the animal. 


TADPOLES AND FROGS. 


191 

Sight. The optic lobes just mentioned are con¬ 
nected with a pair of eyes very much like our own. 
Each eye is really a camera obscura with its lens and 
darkened walls. The image of an external object is 
thrown on the retina , which corresponds to the ground 
glass of a camera and is composed of nervous tissue 
forming the end of the optic nerve. The frog sees well, 


B 



Fig. 149.—Striped Muscle-fibres. A, a fibre much magnified; B, a 
fibre breaking up into fibrillae. 


as is evidenced by the precision with which he strikes 
a fly with his tongue. 

Hearing. On either side of the head is a dark cir¬ 
cular spot which indicates the position of the ear. This 
ear is wholly internal. Under the skin is a membrane, 
or ear-drum, and under that a cavity, the middle ear. 
This cavity connects with the mouth by the eustachian 
tube as in man. Back of this cavity is another, the 
inner ear, containing the nerves which conduct sound 
vibrations to the brain. 

Smell. In the nasal cavities fibres of the olfactory 
nerve are spread out to receive the sensations of smell. 


















192 


ANIMAL ACTIVITIES. 


Taste. Special organs of taste are found on the 
tongue and on the membrane lining the mouth. 

Touch. The skin is well supplied 
with nerves, and there are special 
tactile areas. 

Classification. The frog belongs 
to the division of Vertebrata known 
as Amphibia or Batrachia. They 
receive their name Amphibia from 
the fact that the young live in water 
breathing by gills, while the adult 
forms breathe air. As might be ex¬ 
pected, there are exceptions to this 
|B general rule. The Amphibia are 

1 destitute of scales, the skin being 
3 perfectly naked, and in most cases 

2 provided with peculiar glands. They 

3 have no claws. The Amphibia differ 
^ from the fishes in having a connection 
| between the mouth and nostrils, and 
■j* also between mouth and ear. The 
■5 heart in the adult has three chambers, 
- a ventricle and two auricles. In the 
3 larva the heart is two-chambered. 

All live in fresh water. To this class 
belong the toads, frogs, and sala¬ 
manders. 

Reptiles. Questions similar to 
those used concerning the frog may 
be answered about turtles and snakes. 
Living turtles and snakes are easy to 
obtain and fairly easy to keep alive. 
A large box with glass sides covered 
with wire netting makes a good vi¬ 
varium. Sand and gravel and a dish 
of water should be kept in the bottom of this box. A 
little moss provides a carpet. 

The class Reptilia resembles in many ways the 






















TADPOLES AND FROGS. 


193 


Amphibia. The class includes many animals resem¬ 
bling toads and salamanders, besides the well-known 
turtles, snakes, crocodiles, and alligators. Among 
Reptiles the body is more or less completely covered 



by scales, and when there are any toes these are armed 
with claws. The heart is three-chambered, as in the 
case of Amphibians, except in alligators. The young 
do not breathe by gills as in Amphibia. The eggs are 








194 


ANIMAL ACTIVITIES. 


commonly large and when deposited for hatching out¬ 
side of the body are covered with a limy shell. A 




Fig. 153.—Brain of 
Frog. 01 , olfactory 
lobes; CH, cerebral 
hemispheres ; OpL, 
optic lobes ; Cl, 
cerebellum; MO, 
medulla oblongata. 


peculiarity of the skull of Reptiles is the presence of 
the quadrate bone, a characteristic shared also by 
birds. 















TADPOLES AND FROGS. 


195 



SPINAL COR 


CEREBRU 


•NAL OOLUMN 


UT ENDS OF 
INAL NERVES 


Fig. 154.—Brain and Spinal Cord of M^n. 





196 


ANIMAL ACTIVITIES . 


For Note-book. 



Fish. 

Tadpole. 

Frog. 

Turtle. 

Head and 
Neck. 





Limbs. 





Claws. 





Covering of 
Body. 





Teeth. 





Skeleton. 





Heart and 
Lungs. 





Organs of 
Sense. 





Movements. 









































CHAPTER XVIII. 


BIRDS. 

In birds the skin produces feathers instead of scales 
as in fishes and reptiles. For the study of birds, 
pigeons or English sparrows are easily obtained. Birds 
that are sold for food may be bought at the markets 
and used to illustrate different parts of the work. Living 
birds of some sort should be kept in the laboratory for a 
time while bird-study is going on. Of course nothing 
can take the place of out-of-door work with this class of 
Vertebrata. In answering the following questions a 
living bird should be observed, and stuffed specimens 
of the English sparrow should be in the hands of the 
pupils. 

The Sparrow. Note the shape and color of differ¬ 
ent parts, method of locomotion, both in walking and 
flying, how it eats and drinks and cares for its feathers. 

Do you find eyelids ? Do you find a nictitating 
membrane ? This is a thin membrane at the inner 
corner of the eye. How does the membrane act ? 

Does the bird have ears ? Where are they ? 

Does it have teeth ? How would you describe the 
mouth ? 

Do you find nostrils ? Is the breathing rapid or 
slow ? What do you think about the bird’s tempera¬ 
ture ? 

Does the bird use its wings while walking ? 

What seems to be the use of the tail ? 

Does the bird moult ? 


197 


198 


ANIMAL ACTIVITIES. 


Where does the bird find the oil used in preening its 
feathers ? 

How does the size of a bird’s egg compare with the 
size of its body? How does the size of a frog’s egg 
compare with the size of its body ? 

Are the senses of the bird keen or dull ? Does the 
bird have the same senses as man ? 

How would you describe the song of the bird you 
are studying ? 

The Wing. What is the shape of the wing ? 

How many joints has it ? 

Do you find bones corresponding to those of your 
own arm, forearm, wrist, palm, and fingers ? Use a 
prepared skeleton of a wing. 

How many bones in arm, forearm, wrist, and palm ? 
How many fingers ? Is there a thumb ? Sketch the 
skeleton of the wing. 

Does the skeleton of a frog show a similar structure 
of the arm ? How does the arm of a turtle compare 
with the wing of a bird ? . 

Do you find feathers on the thumb ? on the hand ? 
on the forearm ? on the arm ? 

The Leg and Foot. Do you find thigh, shin, ankle, 
foot, and toes ? Where is the heel ? Sketch the 
skeleton of the leg. 

How many toes ? Do all the toes point in the same 
direction ? 

Are there feathers or scales or both on the tarsus ? 

When scales are present what is their shape ? 

Are there webs between the toes ? 

In a fresh specimen can you find the tendon which 
moves the toes ? How do the toes act in perching ? 

Feathers. Obtain some large feathers from the 
wing or tail of a pigeon or a barn-yard fowl. Notice in 
a single feather the shape as seen in outline. Do you 
make out the shaft and the vane ? Sketch a feather. 

Can you separate the parts of the vane into branches 
of the shaft (barbs) ? 


BIRDS. 


199 


Using a simple microscope, can you find that the 
barbs themselves bear branches (barbules) ? Sketch 
a magnified barb showing barbules. 

What seems to be the use of the barbules ? 

Do the feathers from different parts of the body seem 
to have the same parts ? 

Examine a downy feather and a pin-feather. How 
do those compare with the other feathers ? 

What is the appearance of the skin of a fowl from 
which the feathers have been plucked ? 

Are the pits from which feathers grow equally dis¬ 
tributed over the body ? 

Summary of Drawings, (a) Sketch of skeleton of 
a wing, naming humerus, radius, ulna, carpal, and 
metacarpal bones, and phalanges. 

(< b ) Sketch of a wing covered with feathers. 

(c) Side view of foot and leg, naming femur, fibula, 
tibia, tarsus, metatarsus, and phalanges. 

(d) Sketch of whole feather. 

( e ) Sketch of a barb showing barbules (magnified). 



fiG. 155.— a, beak of snipe, fitted for probing in soft mud ; b, beak of 
sparrow, fitted for cracking seeds ; c, beak of eagle, fitted for tear¬ 
ing flesh ; </, beak of parrot, fitted for cracking nuts ; beak of 
swift, fitted for seizing insects while on the wing ; /, beak of duck, 
fitted for skimming the water. 

The Activities of the Bird. Taking Food. Very 

noticeable is the difference between the bill of a bird 




200 


ANIMAL ACTIVITIES. 


and the jaws of a frog or fish. Noticeable, too, is the 
resemblance between the bill of the bird and that of the 
turtle. The hard toothless mandibles, however, are well 
fitted for the purpose of securing the insects and seeds on 
which most birds feed. Before man invented tweezers, 
the woodpeckers pried into the bark of trees and pulled 
out the hidden insects with their long, strong pliers. 

These illustrations show some of the forms the beak 
takes to make it a better tool for procuring the particu¬ 
lar kind of food on which the bird lives. In addition 
to its other uses the beak often serves as a hand. 

Birds and Insects. Insect-eating birds devour tons 
of destructive pests in our orchards and fields. It has 
been estimated that a single chickadee may destroy 
more than a hundred thousand canker-worm eggs in 



Fig. 156.—The Digestive Organs of a Bird, a, oesophagus; b, crop; 
C, stomach; c, gizzard. 

one day. Even crows feed on insects more than on 
corn. Hawks and owls keep in check field-mice and 
frogs, gulls clean the shores of decaying matter, and 
many of the smaller birds live on the seeds of noxious 
weeds. The importance of preserving bird life cannot 
be easily overestimated. 




BIRDS. 


201 


Nutrition. The processes of nutrition are carried 
on in much the same way as in other vertebrates. In 
most birds the food, when swallowed, passes down the 
oesophagus to an enlargement called the crop, where it 
remains for a short time. It then goes to the stomach, 
which frequently consists of two 
parts, the proventriculus, where 
gastric fluids are poured on the 
food, and the gizzard, where it 
is ground. This gizzard is most 
highly developed in seed-eating 
birds, and commonly contains 
stones which the bird has swal¬ 
lowed and which grind up the 
food that has been softened in 
the crop and mixed with gastric 
juice in the proventriculus. Fig . I57 ._ D iagram of the 

Respiration. Breathing Heart of a Bird, 

occurs by lungs, the air enter¬ 
ing and leaving because of the increase and decrease 
of the size of the body-cavity produced by movements 
of the bones and muscles surrounding it. The expan¬ 
sion of the lungs in breathing is very slight. The lungs 
connect with air-sacs which extend among the other 
internal organs, and even into the bones. These serve 
to increase the bulk of the bird without adding to its 
weight, thus forming a sort of hot-air balloon. 

Reproduction. Eggs are produced in the ovaries, 
and pass from these organs through the left oviduct, 
the right ovary being suppressed in birds, to the cloaca 
and thence out of the body. The cloaca is the 
common cavity into which the alimentary canal, the 
kidneys, and the oviduct empty. 

In its passage through the oviduct the egg receives 
from the walls of this tube its layer of white albumen and 
its calcareous shell. The eggs hatch outside of the body 
and are cared for by the parent birds with much solici¬ 
tude. Except with a few of the most intelligent insects, 





202 


ANIMAL ACTIVITIES. 


there is very little attention given to the young of animals 
lower in the scale of life than birds. Here maternal 
and paternal duties seem of the greatest importance. 

Discovery. The senses of birds are very keen, 
especially those of sight and hearing. There is an 

external opening to the 
ear surrounded by regu¬ 
larly arranged feathers. 
The nervous system re¬ 
sembles that of the fish 
and frog, but the brain 
is much larger in com¬ 
parison with the size of 
the body, the cerebrum 
and cerebellum being 
greatly developed. 

Motion. In this func¬ 
tion birds surpass all 
other animals. Not 
only can some birds 
move through the air 
more rapidly than the 
fastest express train, but 
others can swim most 
skilfully in the ‘water, 
and still others are able 
to run faster than a race¬ 
horse on land. Of 
course, no one bird can do all these things, for when 
wings are greatly developed for very rapid flight, as in 
the swallow, feet are weak and almost useless; and 
when running is specialized, as in the ostrich, wings 
become small and of little use. The swallow does not 
alight even for the purpose of feeding her young. 

In the wing, as we have seen, the bones resemble 
those in the human arm (Fig. 160). At the elbow 
the arm is bent, and the space between the arm and 
forearm is filled with a strong web bearing feathers and 







BIRDS. 


203 



assisting in spreading the wing. There are only three 
fingers, and the bones of these and of the palm and 
wrist are so grown together that it is difficult to distin¬ 
guish them. Connected with the wing are two clavi¬ 
cles, or collar-bones, which unite at their ends to form 
the wish-bone. These, with the scapulars or shoulder- 
blades and the coracoid bones, form the pectoral girdle 
holding the wings in place. 

While the chief organ of flight is the wing, it must 
be remembered that the whole body aids in aerial navi- 


Fig. 159.—A Swallow Feeding Her Young. 

gation. The sternum or breast-bone is large and 
strong and fastened firmly to the ribs. Its surface is 
often increased by a ridge of bone along the middle 
called the keel (Fig. 162). The muscles of the breast 
attached to this sternum move the wings. These 
muscles are dark colored and tough in birds of great 
wing-power and white and tender in barn-yard fowls 
which have lost the power of continuous flight. 




204 


ANIMAL ACTIVITIES. 


Besides this machinery of bone and muscle, the 
whole body of the bird is to some extent a balloon. 



Fig. 160.— A, arm of man; B , fore leg of dog; C, wing of bird; h , 
humerus; r, radius; u, ulna; c, carpus- m } metacarpus; 
phalanges. 



Fig. 161.—A Bird’s Wing. <7, when flying; 6, at rest. 

The feathers increase greatly the amount of air dis¬ 
placed, and hence aid the buoyancy without adding 








BIRDS . 


205 


materially to the weight. The whole plumage of a 
common fowl weighs only about three ounces. 

Having plumage filled with air heated by the body, 
carrying air-sacs in viscera and bones, breathing faster 
than other animals, pumping 
blood more rapidly to all parts 
of its body, and with it, oxygen 
to replenish the internal fires, 
the bird easily rises on the atmos¬ 
phere much as an iron ship floats 
on the ocean. 

Other Voluntary Movements. 

Swimming birds have the toes 
webbed to serve as paddles and 
the form of the body is modified 
to fit it for motion through the 
water. The legs are placed 
farther back so that the propel¬ 
ling power may act from behind. 

In running and wading the struc¬ 
ture of legs, feet, wings and beak 
are wonderfully fitted for their 
peculiar work. 

Not only can birds move from 
place to place in search of food, 
or in undertaking their long 
migrations, but by voluntary movements they are also 
able to perform skilled labor in the building of nests, 
to carry on warfare, and to express the most varied 
emotions. 

Birds and Reptiles. Birds resemble reptiles in 
many ways. They have epidermal scales on some part 
of the body, the digits end in claws, the lower jaw is 
connected to the upper jaw by a quadrate bone, the 
skull is fastened to the first vertebra by a single con¬ 
dyle, true ribs are present, there are no gills, the eggs 
are large, and the digestive, reproductive, and excre¬ 
tory organs empty into a single cavity, the cloaca. 



Fig. 162.—The Sternum 
of a Shrike. 







20 6 


ANIMAL ACTIVITIES . 


Some fossil birds had teeth like reptiles, and at least 
one bird had a long reptilian tail (Fig. 166). Because 
of these resemblances birds and reptiles have sometimes 
been classed together as Sauropsida. 

Classification of Birds. Birds have been most com¬ 
monly classed in accordance with their most easily 


a 



c d 


Fig. 163. — Feathers, a , a quill-feather ; b, quill-feathers fastened to 
wing ; c, a shape-feather ; d, a down-feather. 


recognized points of external structure; this structure 
being dependent largely on the habits of the birds. 

These groups of birds are often spoken of as orders; 
but these orders do not correspond to orders among 
insects. 





BIRDS 


207 


I. The Running Birds (Struthii). The legs are long and 
the wings small. The keel of the sternum is lacking. 
There are two or three toes. Ostrich, emu, kiwi. 

II. The Scratching Birds (Rasores). They have three 
toes in front, and a fourth a little higher, behind. Grouse, 
pheasant, common hen. 



III. Swimming Birds (Natatores). The legs are short, 
and there is a web between the front toes. Penguin, duck, 
gulls, etc. 

IV. Wading Birds (Grallatores). The tarsus is long and 
partly naked. The neck is also long and often the bill. 
Great blue heron, snipe, etc. 

V. Birds of Prey (Raptores). These birds have stout 
curved beaks, strong feet with sharp claws, and large wings. 
Hawk, eagle, owl, etc. 



208 


ANIMAL ACTIVITIES. 


VI. The Pigeons (Columbinae). These birds resemble 
the rasores but have weaker legs, pointed wings, and a fleshy 
membrane at the base of the beak. Pigeon. 

VII. Gimbing Birds (Scansores). Two toes are directed 
forward and two backward, fitting the feet for climbing. 
In parrots the beak is also used for climbing. Parrots, 
woodpeckers. 

VIII. Perching Birds (Passeres). There are three toes 
pointing forward and one pointing backward, all on a level. 
Here belong almost all our common song birds. 


C 



Fig. 165 .—A, foot of a pelican; B, foot of a perching bird; C, foot of 
a kingfisher. 



Questions. What are some common birds of very 
rapid flight ? 

What special adaptations of structure to habit among 
birds can you enumerate ? 

Why do birds migrate ? 

What birds should be exterminated ? 

What birds should be protected ? 

Do birds reason ? 

What evidences of intelligence have you observed 
among birds ? 

Topics for Reports. A List of Birds I Know. A 
List of Birds I have Seen in Winter. Order in which 





BIRDS . 


209 


I Saw New Birds in Spring. Description of a Bird I 
Know Edible Birds’ Nests. Birds on Oceanic 
Islands. The Future of the Domestic Sparrow. Bird 
Pets. Bird Courtships. Bird Migrations. Bird In¬ 
dustries. Superstitions about Birds. Canaries. Do¬ 
mesticated Birds. Parrots. Crows. The Robin. 
Birds in Millinery. Uses of Gulls. What Mr. Bur- 



Fig. 166.—The Archaeopteryx. 


roughs says in “Birds and Bees and Sharp Eyes.” 
Bird Homes. Shapes and Colors of Birds’ Eggs. 
Length of Life among Birds. Falconry. 


VOCABULARY. 


Am phib'ia (Or. amphi, around, or 
on both sides, and bios , life), a 
class of vertebrate animalsbreath- 
ing by gills when young. 

Au'ri cle (Lat. auris, ear), a cham¬ 
ber of the heart for receiving 
blood from the veins. 

Barb (Lat. barba , beardl, one of 
the side branches of a feather. 


Barb'ule (Lat. dim. of barba), one 
of the projections along the edges 
of the barbs of a feather. 

Bat ra'chi a (Gr. batrichos, frog), 
another name for the Amphibia. 

Car'pus (Gr. karpos, wrist), the 
wrist. 

Clo a'ca (Lat. cloaca , a sewer), a 
common cavity into which the 



2 IO 


ANIMAL ACTIVITIES . 


alimentary canal, the kidneys, 
and the oviducts empty. 

Con'dyle (Gr. kondylos , knuckle), 
a bony projection. 

Eu sta'chi an Tube, a passage 
from the throat to the ear. 

Fe'mur (Lat. femur, thigh), the 
thigh-bone. 

Fib'u la (Lat. fibula, a clasp), the 
outer of the two bones of the leg 
below the knee. 

Hu'me rus (Lat. humerus , the 

shoulder), the bone of the upper 
part of the arm. 

Keel, in birds, the ridge of bone 
along the ventral side of the ster¬ 
num. 

Met a car'pus (Gr. meta, beyond, 
and carpus'), the group of bones 
between the wrist and fingers. 

Metatar'sus (Gr. meta , and tar¬ 
sus) , the group of bones between 
the tarsus and phalanges. 

O'vi duct (Lat. ovum, egg, and 
duco , to lead), a tube for the 
passage of eggs. 

Pha lanx, pi. phalanges (Gr. pha¬ 
lanx, battle-line or bone of finger 
or toe), one of the finger- or toe- 
bones. 


Ra'dius (Lat. radius), one of the 
bones of the forearm. 

Ret'i na (Lat. rete, a net), the inner 
coat of the eye. 

Reptil'ia (Lat. reptilis, a rep¬ 
tile), a class of vertebrate ani¬ 
mals. 

Shaft, the midrib of a feather. 

Ster'num (Gr. sternon, breast), the 
breast-bone. 

Tar'sus (Gr. tarsos, a flat surface), 
the ankle. 

Ten'don (Lat. tendo, to stretch), 
a cord or band of connective 
tissue usually binding muscles to 
bones. 

Tib'i a (Lat. tibia), one of the bones 
of the leg below the knee. 

Ul na (Lat. ulna, elbow), a bone of 
the forearm. 

U'ro style (Gr. oura, tail, and sty¬ 
los, a column), the long bone at 
the end of the vertebral column 
in the frog. 

Vane, the web of a feather with its 
shaft. 

Ven'tricle (Lat. ventriculus , dim. 
of venter, the belly), a chamber 
of the heart for forcing blood 
into the arteries. 



CHAPTER XIX. 


MAN’S NEAR RELATIVES (MAMMALS). 

With slight variations, the questions which follow 
can be made to apply to many other animals than the 
cat. With the limited time usually allowed for the 
study of mammalia, abundant material among common 
domesticated animals is easily within the reach of all 
pupils. 

The Living Cat. With what is the body covered ? 

Do you find the same parts of fore and hind limbs as 
in the frog ? 

How many toes has the cat on the fore foot ? on the 
hind foot ? 

Can the claws of the cat be withdrawn ? 

Can the claws of a dog be withdrawn ? 

On your own hands where are the parts correspond¬ 
ing to the pads on the fore foot of the cat ? 

Can you find the cat’s elbow, wrist, knee, and heel ? 

Does the cat ever walk or creep with the heel touch¬ 
ing the ground ? 

In the human body the tendon of Achilles is the 
strong band connecting the heel with the muscles of 
the calf of the leg. Can you find this tendon in the 
cat ? 

Are the cat’s vertebrae capable of more or less motion 
than those of the frog ? Than those of a bird ? 

Do the vertebrae extend into the tail ? 

Does the sternum seem as large as in most birds ? 
Why should there be a difference ? 


211 


212 


ANIMAL ACTIVITIES. 


Do both upper and lower jaws move ? Can the 
jaws move sidewise ? 

How many teeth has a cat ? How do they differ in 
shape from those in the human body ? 

The dental formula for man is written z'f, c\, pin\, 
m\. This means that in man there are in each half¬ 
jaw two incisors, or cutting teeth, 
one canine or pointed tooth, two 
premolars, small grinding teeth, 
and three molars, large grinding 
teeth. Write the dental formula 
for the cat. 

What peculiarity do you notice 
Fig. 167.—Teeth of Man. about the tongue of the cat ? 

Are the long hairs near the 
cat’s mouth especially sensitive ? Do you think they 
are of any use to the cat in searching for prey ? 

What is the shape of the external ear of the cat ? 
In what direction do the ears point ? Are they better 
fitted to hear noises in front or behind ? 



Fig. 168.—Teeth of Dog. 


How do the cat’s ears compare with those of a 
rabbit ? What difference in habit may be indicated by 
the difference in ears ? 




MAN'S NEAR RELATIVES (MAMMALS). 213 

In the cat’s eye can you make out the cornea (white 
of eye), the iris, and the pupil ? 

Is the pupil of the cat’s eye of the same shape at 



Fig. 169.—Teeth of a Sheep. 


midday as at night ? How do you account for the 
difference ? 

Do you find the rudiment of a nictitating membrane ? 
Does the cat have an acute sense of smell ? What 
reasons have you for your answer ? 

How does the cat nourish its young ? 



Fig. 170.—Teeth of Hare. 


Summary of Drawings, (a) The eye of a cat as 
seen at noon, and at night. 

( b ) Sole of fore foot of cat showing pads. 


214 


ANIMAL ACTIVITIES . 


Using the same questions as have been used con¬ 
cerning the cat, except such questions as obviously do 



Fig. 171.—Skull of Cow Showing Teeth. 

not apply, write a description of the horse. Answer 
also these additional questions: 



Fig. 172.— The Human Eye. 

How does the food of a horse differ from that of a 
cat ? How do the teeth differ in shape ? 






MAN'S NEAR RELATIVES {MAMMALS). 215 

How does the end of the horse’s toe compare with 
the cat’s toes ? 

How does the distance between heel and end of toe 



Fig. 173.—Skeletons of Man and Horse. After Flower. S, shoulder; 
E, elbow; IV, wrist; H, hip; A", knee; A, ankle. 


on the horse compare with the same measurement on 
the cat ? 

What difference in habit corresponds to the difference 
in structure of the foot and leg ? 

Write resemblances and differences for horse and 
cat. 









ANIMAL ACTIVITIES. 



174.—Bones of Leg and Arm of Man. 


Fig. 175,— Vertebral 
Column of Man. C, 
cervical; D, dorsal; 
-L, lumbar. 



MAN'S NEAR RELATIVES {MAMMALS). 


217 


Summary of Drawings, (a) Side view of fore and 
hind leg of horse. 

{&) Side view of head of horse. 

Other Mammals. As far as possible the above 
questions should be answered for the rabbit, squirrel or 


A 



Fig. 176.—Human Skull. A y base of skull showing condyles at 13, 13. 

mouse, cow or sheep, and several other mammals 
which can be easily observed by the pupils. 



2 l8 


ANIMAL ACTIVITIES. 


The Mammalian Skeleton. For this study the 
class should be provided with at least one entire 
mammalian skeleton. A sheep’s head, with the 
vertebra of the neck, and a sheep’s legs may be 
bought at almost any market. The muscles and 
tendons can be easily removed after boiling. Heads 
and limbs of fowl, rabbits, frogs, and other ver- 


P 



Fig. 176.—Human Skull. B , side view. 


tebrates should also be obtained at the markets 
and prepared for class use. A human skeleton, or 
a large chart showing the bones of the human 
body, should be used as a basis for comparison. 
Indeed a number of charts, showing parts of 
skeletons of a variety of mammals, should be at 
hand. 


MAN'S NEAR RELATIVES (MAMMALS). 


219 


The Fore Limbs. The bones of the fore quarter of 
a sheep fastened to a board in their proper positions 
serve well as the objects of this study. 

Do you find humerus, radius, ulna, carpal bones, 
metacarpal bones, and phalanges ? 


B 



Fig. 177.—First and Second Vertebrae of Man. A, axis; B , atlas; 6,6, 
sockets for condyles. 


Do you find the same number of carpal and meta¬ 
carpal bones as in man ? 

How many fingers do you find ? How do they 
compare in position and length with those of man ? 

What difference in use corresponds to the differ¬ 
ence in structure of hand and wrist in the sheep and 
man ? 

In the pectoral girdle do you find shoulder-blade 
(scapula) and collar-bone (clavicle) as in man ? How 
do you account for the difference ? 

Drawing. Sketch of the fore leg of the sheep, 
naming the parts. 

The Hind Limbs. Do you find femur, tibia, fibula, 
tarsal bones, metatarsal bones, and phalanges ? 

Do you find the same number of tarsal and meta¬ 
tarsal bones as in man ? (See Fig. 174.) 

How many toes do you find ? How does their 
number compare with those in man ? In the cat ? In 
the horse ? In the frog ? In the turtle ? 


220 


ANIMAL ACTIVITIES. 


How many bones compose the pelvic girdle ? 

By what kind of a joint is 
the femur attached to the 
pelvic girdle ? 

Drawing. Hind leg., 
naming bones. 

The Axial Skeleton. How 

many vertebrae compose the 
back-bone ? 

How many ribs are present ? 
How many of these are fast¬ 
ened to the sternum ? 

How does a mammalian 
vertebra compare with a verte¬ 
bra of a fish ? 

How does the vertebral 
column in a mammal differ 
from that in the frog ? 

The vertebra on which the 
skull moves is called the atlas, 
the vertebra next back of that 
is called the axis. Can you 
find on the atlas smooth sockets corresponding to pro¬ 
jections on the skull ? 

The projections on the skull are called condyles. 
How many condyles are there on the mammalian 
skull ? How many on the bird’s skull ? What purpose 
do condyles and sockets serve ? 

Do you find a quadrate bone on the mammalian 
skull ? 

What is the dental formula of the mammal you are 
studying ? 

What is the dental formula for the horse ? For a 
squirrel ? For a rabbit ? 

In the head of a horse, how does the area of face and 
cranium compare with the same areas in man ? 

(See figures.) Write resemblances and differences 
for skull of gorilla and man. 



Fig. 178. —Skeleton of Go¬ 
rilla. 



MAN'S NEAR RELATIVES {MAMMALS). 


221 


(See figures.) Write resemblances and differences 
for limbs of gorilla and man. 



Mammalian Viscera. From a tanned or alcoholic 
specimen showing the internal organs of a rat or other 
small mammal answer these questions: 














222 


ANIMAL ACTIVITIES . 


Do you find the visceral cavity divided by a thin 
muscular wall (the diaphragm) ? Is there a diaphragm 




in the frog or fish ? In the bird ? How does the dia¬ 
phragm assist in breathing ? 

Can you find the lungs and heart ? Are they an¬ 
terior or posterior to the diaphragm ? 





MAN’S NEAR RELATIVES {MAMMALS). 


223 


Is the liver anterior or posterior to the diaphragm ? 
Drawing. The internal organs in position, showing 
only lungs, heart, diaphragm, 
liver, stomach, and intestine. 

The Class Mammalia. The 
mammals bring forth their young 
alive, and nourish them during 
infancy by milk secreted by the 
mother. They have warm blood, 
and in almost all cases the body 
is covered with hair. 

The vertebrae in the mammals 
are usually flattened. The skull 
moves on the first vertebra by 
means of two condyles. There 
is no quadrate bone. All have 
the fore limbs, and nearly all 




Fig. 181.—Arm and 
Hand of Man. 


Fig. 182. —Skeleton of Chim¬ 
panzee Showing Hand. 


have also the hind limbs. Normally there are five 
toes on each foot. Almost all mammals have teeth, 




224 


ANIMAL ACTIVITIES . 


and very many have two sets, the milk-teeth and the 
permanent teeth. The visceral cavity is divided by 
the diaphragm into two parts, the thorax or chest, and 
the abdomen. External ears are present in most cases. 
The heart has four chambers (Fig. 179). 

The nervous system differs from that of other verte- 





Fig. 183.— Fore Foot 
of Mole. 


Fig. 184.— Fore Foot of Cat. 

a, with claws extended; 

b, with claws drawn in. 


brates largely in the greater size of the cerebrum or 
forebrain. 

Fingers and Toes. As we have already pointed 
out, the mammals have normally five fingers for each 
hand or fore foot, and five toes for each hind foot. In 
many different ways these digits have been changed 
and adapted to their special work, yet the fundamental 
plan of structure has remained unaltered. Our own 
hands are the most perfect animal tools in existence, 
capable of manifold and delicate movements, but they 
do not differ as much from the fore feet of cats, bats, 
or even whales as we might at first suppose. The chief 
point of superiority in the human hand is found in the 
position and scope of movement of the thumb. In 
some of the higher monkeys the thumb is opposed to 
the fingers very much as in man, but in all cases the 


MAN'S NEAR RELATIVES {MAMMALS). 


225 


power of movement is much less, and the whole hand 
is far more clumsy; yet the hands of men and the hands 
of monkeys possess almost identically the same bones, 




Fig. 185. —Fore Feet of Cow. Vig. t86.— Fore Feet of Horse. 

tendons, and muscles. They have also the small 
callous, or hard, parts of the palm, with thick cushions 
of fat beneath, to protect the working parts between 



Fig. 187. —Foot of Elephant. Fig. 188.—Feet of Bear. 


the outer skin and the hard bones. These callous 
spots are easily seen, too, in the fore feet of cats, dogs, 
bears, and many other mammals, and they may, with 





226 


ANIMAL ACTIVITIES. 



Fig. 189. — A y sole of foot of man; B, of dog; C, of horse; a, heel; by 
callous; c, cushion; I .— V., digits. (From Flower, “The Horse .") 








MAN'S NEAR RELATIVES {MAMMALS). 


227 


some care, be found even in a hand or fore foot so 
much specialized as that of the horse. 

Hands and Feet. As we have already found, the 
bones of the hind feet closely resemble those of the fore 
feet, or, in other words, hands and feet are built on the 
same plan. The palm of the hand corresponds to the 
sole of the foot, showing the same ridges and callosities. 
Animals which put the whole sole of the foot, from toe 



Fig. 190. —Finger of Man and of Horse. After Flower. a t callous; b, 
cushion; c, nail. 


to heel, on the ground when they walk are said to be 
plantigrade animals. Quadrupeds, like the bear, which 
walk in this way have a somewhat awkward gait. The' 
more graceful and easy runners among beasts walk on 
the ends of their toes. These are said to be digitigrade 
animals. The horse presents an extreme illustration 
of the digitigrade foot, walking as he does on the ends 
of his middle toes and middle fingers. We, ourselves, 
walk on the whole sole of the foot, but when we run 
we rise on the toes. If we should attempt to walk on 
all fours, bearing the weight of the body on soles and 







228 


ANIMAL ACTIVITIES. 


palms, we could hasten only by rising on fingers and 
toes. Should we so rise it is easy to see that the little 
finger and the thumb would not touch the ground. 
They would hang as useless members behind the 
other fingers. Rising still more, the weight would rest 
wholly on the middle finger, and two more fingers 
would become useless. Something like this has prob- 
'ably taken place gradually in the development of digi- 
tigrade feet. 

The Horsed Foot. The ancestry of the horse has 
been traced back very carefully for thousands of years 



Fig. 191.— Feet of Ancestors of Horse. The figures indicate the num¬ 
bers of the digits in the five-fingered hand of most mammals. 


before man dwelt upon the earth. It has been found 
that the horse is probably a descendant of a five-toed 
animal not much larger than a sheep. From this 
animal the line of descent has been followed down 
through the ages, the various forms showing the loss 
of toes, one after another, until only one now remains 
for each foot. The splint bones seen on each side of 
the long metacarpal and metatarsal bones of the horse 
are all that remain of the two toes which last dis¬ 
appeared. 















MAN'S NEAR RELATIVES {MAMMALS). 229 

Growth from the Epidermis. Hair, claws, hoofs, 
and horns are all made of the same substance as our 
own finger-nails. All are modifications of the epider¬ 
mis or outer skin. In its growth a hair dips down into 
the true skin, forming a papilla which is sunken into 
the dermis or true skin. This papilla is provided at 
its base with glands for oiling the hair, muscles for 
erecting, blood-vessels for nourishing, and nerves for 



Fig. 192.— Growth of Hair. A , hair-rudiment; B, hair-rudiment with 
young hair formed, but not yet risen through the cuticle; C, hair 
protruded. 


warning. When the hair is long and twisted we call 
it wool, when smooth, fine, and soft we call it fur. 
On the pig the coarse, straight hairs are called bristles. 
The quills of a porcupine are stout hairs with sharp 
points, very useful to the animal in defending itself from 
enemies. Hairs are colored by pigment-cells found in 
each hair. Commonly among wild animals the color 
of the hair serves to conceal the wearer from enemies; 


23 ° 


ANIMAL ACTIVITIES. 


in many cases even changing with the seasons to afford 
a better protection. The arctic fox and the northern 
hare become near as white as snow in winter. It has 
been found that the fact that most animals are lighter 
in color beneath than above is really a device for con¬ 
cealing them. 

Horns. These defensive weapons are formed from 
the epidermis in much the same way as hair. In 



Fig. 193.—1, horns of sheep; 2, horns of cow; 3, horns of deer. 


domestic cattle the horns have an interior core of bone 
over which the skin of horn fits. The horns of deer 
are solid, but in the velvet are covered with epidermis. 
They fall off each autumn and grow again in the spring. 

Structure of Teeth. The teeth of mammals are 
composed chiefly of a bony substance called dentine, 



MAN'S NEAR RELATIVES {MAMMALS). 231 

and a harder substance called enamel. In a human 
tooth the enamel covers entirely the outside of that 
part of the tooth known as the crown. The root, or 
fang, of the tooth is covered by a substance called 
cement. The greater part of the tooth is dentine. In 
the teeth of many animals which must grind their food 
for a long time the enamel and dentine are so folded 
together that hard sharp ridges of enamel are produced 
above valleys. When these valleys are deep they are 
filled with cement, as in the case of the molar teeth of 



Fig. 194.— Skull of Cow Showing the Bone of the Horn. 


the horse. As these teeth wear away the dentine and 
cement wear faster than the enamel and the ridges 
become more prominent. 

Gnawing animals, like the squirrel, have teeth fitted 
with enamel in front and dentine behind. As the teeth 
are used the dentine is worn away and a sharp chisel 
of enamel is produced. These teeth constantly increase 
in length from below, and, if they are not worn away 
fast enough, they sometimes grow so long that they 
cannot be used at all and the animal starves. In every 



232 


ANIMAL ACTIVITIES. 


animal the teeth seem to be especially adapted for the 
work they must perform. 

Questions. Refer to Figs. 178, 195, and 196. 



rmmme 


Fig. 195.—A Manlike Ape Walking. 


In what way does a gorilla or a chimpanzee resemble 
man ? 

How does man differ from these animals ? 









MAN’S NEAR RELATIVES {MAMMALS). 


233 


In what respects are the monkeys peculiarly well 
fitted for their environment ? 

How do monkeys differ from dogs ? 

In the struggle for existence what advantages do 



i 


Fig. 196.—A Chimpanzee. 


monkeys have over dogs ? What advantages do dogs 
have over monkeys ? 

How do monkeys differ from horses ? 

In what respects do they resemble horses ? 






234 


ANIMAL ACTIVITIES . 


What are the most easily recognized characteristics 
of Fishes ? of Amphibians ? of Reptiles ? of Birds ? of 
Mammals ? 

What is the dental formula of an animal you have 
examined ? 

How do the teeth of a cow differ from those of a 
squirrel ? 

How does hair differ from wool ? 


FOR NOTE-BOOK. 


MAN'S NEAR RELATIVES {MAMMALS). 235 


Man. 









Horse. 









Cat. 









Bird. 









Turtle. 









Frog. 









Tadpole. 









Fish. 










Limbs. 

Fingers and Toes. 

Covering of Body. 

Teeth. 

Locomotion. 

Respiration. 

Organs of Discovery. 

Care of Young, 










































































CHAPTER XX. 


THE DISTRIBUTION OF ANIMALS. 

Distribution in Land, Water, and Air. We have 
already discovered that we must look in different places 
to find different animals. We should not think of 
searching for bees in a desert, nor for cockroaches in 
the fields along with grasshoppers and crickets. We 
have learned that the larvae of dragon-flies and mos¬ 
quitoes live in the water, while the full-grown insects 
inhabit the air. We do not expect to find caterpillars 
either swimming or flying. The place in which an 
animal lives is called its habitat. Animals living 
mostly in the air are said to be aerial , those inhabiting 
the dry land terrestrial , and those dwelling in the 
water aquatic. Aquatic animals may be either fresh¬ 
water or marine forms. 

Distribution in Altitude. In either of the above 
cases the distribution seems to be influenced by alti¬ 
tude, or, as we speak of it in the case of aquatic animals, 
by depth. One species of butterfly is found only on 
the summits of the White Mountains in New Hampshire; 
others are always seen flying near the ground in the 
valleys, while still others live in mid-air. Among 
marine animals this dependence on altitude is very 
marked. If the piles of a wharf be examined at low 
tide we find the animal life marked off into distinct 
zones parallel with the various levels of the water. 

Distribution Over the EartlPs Surface. We are 
familiar with the fact that certain animals are charac¬ 
teristic residents of definite portions of the world. 
Animals belonging exclusively to arctic, temperate, or 

236 


THE DISTRIBUTION OF ANIMALS. 


237 


tropical regions are well known to every intelligent 
person. In the same zone, too, different regions vary 
greatly in the life they support. The bison and grizzly 
bear belong to North America. The gorilla is found 
only in the forests of the western coasts of Africa. 
New Zealand has no native mammals except bats. 
Monkeys with prehensile tails live only in the New 
World. Continents have animals very different from 
those living on islands very near their borders. 

On the other hand, the domestic fly flourishes every¬ 
where, and the house-sparrow seems to thrive as well 
in America as in Europe. Distribution over the earth’s 
surface is often called Geographical Distribution. 

All the animals inhabiting a given region constitute 
its fauna , just as the plants inhabiting a locality consti¬ 
tute its flora . 

The entire region inhabited by a certain kind of 
animal is often called its area of distribution. In the 
case of animals which migrate or wander from place 
to place the area of distribution may be spoken of as 
the range. 

Dispersals. In modern as well as in ancient times 
many animals have greatly extended the areas in which 
they live. The changes made in recent years have 
been carefully studied, to furnish a guide in explaining 
the movements of animals in the past. Doubtless 
many of the same causes which influence animal dis¬ 
tribution now have been always active. 

The Milkweed-butterfly. The milkweed-butterfly 
is an American insect. In about the year 1845 it first 
appeared in the Hawaiian Islands. At about the same 
time its special food-plant (Asclepias) appeared and 
became a troublesome weed. This butterfly soon 
spread over many of the Pacific islands, following the 
spread of its food-plant. It has also extended eastward 
to Bermuda, and is sometimes found in England and 
France. In this case the dispersal has been aided by 
commerce; for the seeds of the food-plant as well as 


238 


ANIMAL ACTIVITIES. 


the eggs, or young, of the butterfly were doubtless 
transported in cargoes carried by ships. It is interest¬ 
ing to note, however, that the animal follows the 
spread of the plant on which its larva lives. 

The Colorado Beetle. This insect, which was first 
described in 1824, was then found only in the neigh¬ 
borhood of the Rocky Mountains. Its food then was a 
wild plant, the sand-burr (Solanum rostratum). When 
the potato in its westward journey reached this beetle, 
the insect eagerly adopted the new food. For about 
forty years the potato-beetle has been extending its 
ravages, until it now flourishes in large numbers 
throughout the United States and Canada, apparently 
defying man’s best efforts to keep it in check. Here 
a change in the food-plant seems to have been respon¬ 
sible for the change in distribution. 

Some Causes of Dispersal. As shown by the cases 
just described, dispersal is often brought about by 
changes in food. Indeed, most of the wanderings of 
animals are doubtless prompted by some impulse con¬ 
nected with food-supply. Other causes, however, like 
pressure by enemies, change, in climate, overcrowding, 
perhaps even the curiosity of the animals themselves, 
have been instrumental in bringing about migrations. 
The regular migrations of birds, during which many 
thousands of our common birds travel half the length 
of a continent in a few weeks, or possibly a few days, 
or the somewhat similar migrations of fish, have not yet 
been fully explained. 

Barriers. Rivers, seas, and sometimes mountains 
have often prevented some of the animals of a region 
from getting far away from their home areas. These, 
restricted animals often characterize a region. In a 
somewhat arbitrary manner naturalists have divided 
the surface of the earth into areas of distribution, for 
greater convenience in studying the causes which have 
brought our present faunas to their present places. 
These areas are often shown by maps. 


* 


THE DISTRIBUTION OF ANIMALS. 


239 


Islands. The ocean is a barrier which land animals 
seldom cross. Because of this, islands far from con¬ 
tinents have both a fauna and a flora differing from that 
of the nearest mainland, and differing also from one 
another. Frogs and toads are not found on oceanic 
islands because salt water has prevented their migration 
to these places. Bats, birds, and butterflies may, 
however, overcome more easily the barrier of the sea, 
and make their homes on these islands. Some large 
islands, like New Zealand, show faunas curiously 
resembling the ancient faunas of Europe or America. 
Doubtless, in such cases, the barrier of the sea has 
preserved the ancient life by preventing the incoming 
of strong invaders. Because of facts like these island 
faunas are of great importance to Zoologists. 

Isolated Tracts. Other regions of the earth may 
resemble islands in their animal life because they are 
surrounded by barriers which certain species cannot 
cross. Thus, the part of a river above a cataract will 
have aquatic animals different from those below the 
falls. 

Most arctic animals perish when brought to southern 
climates. Animals living in the lowlands of equatorial 
regions cannot live on the highlands. Thus heat and 
altitude may prove as effective barriers as the sea itself 
in isolating species. All over the world there are 
tracts characterized by the presence or absence of 
certain plants or animals. 

Wanderings. Whenever an animal wanders into an 
unfamiliar region, differing from its original habitat, we 
wish to know what causes operated to bring about the 
change of location, how the animal supports its life 
under the new conditions, whether it is likely to exter¬ 
minate or reduce the numbers of any of the original 
inhabitants of the locality, and, finally, whether its 
own structure will be gradually modified to adapt itself 
better to the new conditions of life. In regard to 
many cases of change of dwelling-place these questions 


2 40 


ANIMAL ACTIVITIES. 


have been answered. The Colorado beetle has been 
able to maintain itself under new conditions. The 
domestic (English) sparrow thrives in America. In 
these cases the creatures have .adapted their mode of 
life to new habitats with marvellous rapidity and suc¬ 
cess. Foreign rats have practically exterminated 
American species, being able not only to survive, but 
to drive out animals already adapted to their environ¬ 
ment. Fishes in caverns have lost the use of their 
eyes, either from lack of use, or because eyes in abso¬ 
lute darkness are a disadvantage, and so disappear by 
the process of natural selection. 

Structure and Habitat. In the chapter on Insect 
Adaptations we have called attention to the fitness of 
organs for the work they must perform. At first 
thought it might seem as if these insects had been 
fitted from the start for their peculiar mode of life. 
But a little reflection must show that many of these 
adaptations, however ingenious they may seem, are 
really very imperfect. The breathing-organs of aquatic 
insects are clumsy, compared with the gills of a fish. 
In fact, they are soon seen to be modifications of organs 
intended for another purpose, namely, for breathing 
air. If, then, we were to hold that animals were orig¬ 
inally adapted for the localities in which we find them, 
the useless eye of the blind fish in a cavern would be 
to us an insoluble problem. Fish made on purpose for 
life in dark caverns should have no eyes, no optic 
nerves, and no useless muscles to move the eyeballs. 
The fact that all aquatic insects have tracheae admits 
of no reasonable explanation unless we assume that 
these insects are descended from air-breathing ances¬ 
tors. Such ancestors may have entered the water in 
search of food, or to escape enemies. In either case, 
those whose tracheae were best fitted to use the air 
dissolved in the water survived, while their kindred 
perished. 

The obvious inference from the facts of distribution 


THE DISTRIBUTION OF ANIMALS. 


241 


is that the great majority of animals now inhabiting the 
world have become adapted to their present environ¬ 
ment through gradual changes in structure. 

Geological Distribution. It is doubtless true that 
the present distribution of a species has resulted from 
the conditions of its past distribution, even to the 
remotest times. Thus time becomes an important 
factor in the study of animal life. This is especially 
so if it be true that natural selection has operated in 
bringing about other changes, just as it has in altering 
the color of butterflies. Distribution in time is often 
called Geological Distribution. Indeed, to really 
understand an animal structure we need to study not 
only its present ways, but also the history of the 
struggles of its ancestors. In one way or another 
habits, structure, adaptations, and present and past 
distribution are so closely connected that while studying 
one we must study all. 


FOR NOTE BOOKS. 

Lists of Animals Known and Easily Recognized by the Pupil. 


242 ANIMAL ACTIVITIES. 


<u 

•a 

-H 

c £ 
~ o 

s is 

_o 

13 

cc 


</) 

<y 

•o 

cJu 

c 

•=s 

,2 w 

2 > 

w 

<U 

CC 


nj 

c n 

a 

CD 

Q 

oT 

c 

*n 


D 

cr 

< 


</i 

<L> 

u 

U 

<U 

H 


v 

< 




















CHAPTER XXL 


ANIMAL RELATIONSHIPS. 

Classification. In the earlier days of zoological 
research, animals were classified by their resemblances 
and differences as shown by adult forms. As informa¬ 
tion concerning animal structure increased it became 
more and more difficult to arrange schemes of classifi¬ 
cation. The well-known classification of Cuvier divided 
the whole animal kingdom into four great groups: 
Radiates, Mollusks, Articulates, and Vertebrates. 
This classification assumed that species are changeless, 
and the subject of kinship was not considered of so 
great importance as it is now. 

Because of the increasing study of relationships, 
these groups were gradually abandoned for new ones. 
Radiates became Protozoa, Porifera, and Coelenterata; 
and Articulates became Arthropoda and Vermes. 
Many other changes have been made, and similar 
changes are constantly being made, because relation¬ 
ship by descent is now thought to be of so great 
importance. Indeed, relationship is nowadays con¬ 
sidered to be of far more consequence than classifica¬ 
tion. 

Structure. Resemblance in structure must always 
be the most important guide in discovering relation¬ 
ship, as it has always been the basis of classification. 
But such resemblances must be more than superficial, 
and they must be sought for in other than the common 
adult forms of animals. 


243 


244 


ANIMAL ACTIVITIES. 


Fossil Forms. Much light has been thrown on the 
subject of animal kinships by a study of the animals 
which have previously lived on the earth. The history 
of these animals is written in the rocks where their 
rossil remains are found. From a study of these 
femains it is generally believed that the first animals 
existing on the earth were Protozoa. In general, we 
may say that the older the rocks the simpler are the 
fossil forms found in them. 

Were it not for the evidence furnished by fossils, we 
should hardly suspect that the first-known horses were 



Fig. 197.— Feet of Ancestors of Horse. The figures indicate the num¬ 
bers of the digits in the five-fingered hand of most mammals. 


five-toed animals about the size of foxes. America 
when discovered had no living horses, yet wild horses 
are now found in Central and South America. These 
wild horses are in part the descendants of domestic 
animals brought to this continent by man; but some 
are also, doubtless, descendants of animals like those 
whose remains are found in American rocks. 

Among the fossil forms, too, we find the remains of 
many animals having characteristics shared by widely 
differing groups of animals of the present day. Such 
animals are supposed to be the ancestors of the differ- 


















ANIMAL RELATIONSHIPS. 


245 


ent groups which now repeat some of their most im¬ 
portant characteristics. Well-known examples of these 
forms are the Pterodactyl, a flying reptile, and the 
archaeopteryx, a reptile-like bird. 

We do not know that any living birds or reptiles 
have descended directly from the archaeopteryx, but it 



Fig. 198.—A Pterodactyl 


certainly seems probable that birds and reptiles are in 
some manner related by descent. However we may 
interpret the records in the rocks, it is certain that no 
accurate classification of animals based on kinship can 
be made without a careful study of fossils. 








246 


ANIMAL ACTIVITIES. 


Embryology. The sea-squirts, called also ascidians 
and tunicates, were once classified as belonging to the 
Mollusca, and later to the Vermes. Zoologists now 
class these animals with the Chordata, because a study 
of their development shows decided vertebrate charac¬ 
teristics, which disappear with maturity. The larval 
forms of some of these animals resemble the tadpoles 
of frogs, showing the notochord and the gill-slits 
so characteristic of vertebrate animals. Here it is the 



Fig. 199.—The Archaeopteryx. 


larval stage alone which shows the true relationship of 
the animal. 

As already pointed out, barnacles and fish-lice do 
not show in adult life the characteristics which would 
place them among Crustacea. In many other cases of 
similar degeneracy the true kinship can be found only 
by referring to embryonic stages of growth. 

Another simple animal classed with the Chordata is 
the lancelet, or amphioxus, a headless, semi-trans¬ 
parent, boneless creature, which resembles the early 



ANIMAL RELATIONSHIPS. 


247 


stages of growth of higher Chordata, and never ad¬ 
vances beyond this embryonic condition. These illus¬ 
trations show us that embryonic conditions must be 
known in order to classify by relationship. 



Fig. 200.— Diagram of a Sea-squirt, a, mouth; b, vent; c , gullet-open¬ 
ing; d, nerve-ganglion; e, stomach; /, test or outer layer; g , tunic 
or inner layer; h, branchial sac. 


In studying the frog, attention was called to the fact 
that the lungs are formed by simply pushing out the 
walls of the throat. The air-bladder of a fish, and our 
own lungs, are formed in the same way. The air- 



Fig. 201. —Amphioxus. a , mouth; b , c, heart; d, liver; g, respiratory 
organs; h-p , digestive canal; /, notochord; m, spinal marrow; o , 
tail-fin. 


bladder of the fish is less complicated than the lung of 
the frog, and our own lung is more complicated. The 
process of growth, however, is equally simple in all 














248 


ANIMAL ACTIVITIES. 


cases, the difference being only in the amount of fold¬ 
ing. The liver and pancreas of vertebrates arise in the 
same way, by folding of the walls of the food-tube. 

Other changes take place in as simple a way as this. 
Indeed, nearly all the organs of a complex body arise 
by foldings and pushings of layers of cells. When the 
egg of a very simple animal, like the hydra, develops, 
it first divides into a number of cells forming a spherical 



E 


Fig. 202. —Growth of Frog’s Lung from Primitive Food-tube. 

body, the morula stage. One side of this sphere is 
then pushed in until two layers of cells have been 
brought near together, the gastrula stage. In animals 
higher than the hydra a third layer grows between the 
other two, and from these three layers, by pushings 
and pullings and foldings, the parts of a complicated 
animal body arise. These morula and gastrula stages, 
more or less obscured in many cases, have been found 
in the development of all the higher animals. The 



ANIMAL RELATIONSHIPS . 249 

fact that such important changes occur so easily during 
growth leads us to believe that adult forms may undergo 
modifications by processes as simple as these foldings, 
if time be allowed for gradual changes through many 
generations. 

We have noted the gradual disappearance of the tail 
of the tadpole as it reaches maturity. This tail is use¬ 
ful to its possessor for a time, and dwindles away when 
no longer needed. The tail, and the gills as well, 
suggest a relationship between frogs and fishes. If we 



Stage. 



Fig. 204.—Gastrula Stage. A, outer layer 
of cells; B , inner layer; C , external open¬ 
ing, or mouth; D , internal cavity. 


examine the embryo of a bird we find, at an early 
period, a well-formed tail which can be of no possible 
use to its owner. This tail disappears, as does that of 
the frog, with further growth. Even more strongly 
than in the case of the frog is relationship with tailed 
vertebrates suggested. Naturalists generally believe 
that this tail is a peculiarity inherited from a reptile-like 
or fish-like ancestor. Fossil forms like the archae¬ 
opteryx strengthen this opinion. Many other parts of 
animal bodies noticed in the process of growth are 
equally useless to their owners. These are now com¬ 
monly regarded as inheritances from ancestors to whom 
these parts were useful. Thus, the possession of gill- 




2 5 0 


ANIMAL ACTIVITIES . 


slits in the embryos of almost all the Chordata suggests 
a kinship, through inheritance, among the group. 

Distribution. We have noted that aquatic insects 
breathe air by using organs like those of terrestrial 
insects. From this fact it is commonly inferred that 
the ancestors of such insects were terrestrial or aerial. 
Animals which have wandered into a new environment 
have sometimes so changed their mode of life and 
their structure as to form a new species differing from 
the ancestral forms common to the old locality. In 
cases like these relationships could not be detected by 
structure alone. Hence the facts of distribution must 
be reckoned with in determining kinship. 

Mimicry and Protective Devices. As we have 
seen, the real characteristics of an animal may be 
obscured by the devices it has adopted for its better 
protection; hence these devices, too, must be con¬ 
sidered in connection with relationships. 

Heredity. We expect the young of an animal to 
grow into a form like that of its parent. Every egg of 
any kind of animal goes through a definite course of 
development which is essentially like that of every 
other egg of the same species. Eggs of two different 
species may develop exactly alike for a time, but they 
diverge as development goes on. Each egg is true to 
its kind. This fact of the continual repetition of 
ancestral traits we call heredity. Experience shows 
that there are limits to heredity. The young is the 
product of two parents, and these are not exactly alike. 
Young animals from the same parents differ in many 
ways. In any case, however, the differences do not 
impress us much. With heredity it is the resemblance 
to ancestors which is the striking fact, and this resem¬ 
blance is of great assistance in tracing an animal’s 
ancestry. 

Variation. Divergences from the regular path of 
heredity are called variations. For the most part we 
do not know the causes of variations. That such var- 


ANIMAL RELATIONSHIPS. 


2 5 * 


iations occur, and that they may be inherited, is cer¬ 
tain. 

If a florist wishes to obtain a new variety of a certain 
plant, he watches for variations; and by carefully 
selecting those plants which vary in the desired manner, 
he is able, after several generations, to produce what 
he wishes. 

As we have previously pointed out, variations which 
help an animal to maintain its place against enemies, 
and in the face of obstacles, are the ones likely to be 
transmitted to offspring, and so perpetuated. Natural 
selection, which depends on both heredity and varia¬ 
tion, must be considered in determining the relation¬ 
ship of animals. 

A Genealogical Tree. To show relationships, resort 
is often had to devices known as genealogical trees. 
These are supposed to show the ancestry of animals. 
As so many facts must be known to determine ances¬ 
try, such schemes must always be considered as only 
attempts to show relationships in a very general 
manner. Greater knowledge may at any time compel 
changes to be made. 

Classification. A scheme of classification should 
tell the same story of kinship as the genealogical tree. 
It must also be subject to change, for the same reasons 
as the tree. At present there is no classification of 
animals acceptable to all the persons qualified to judge 
of such matters. What follows is a somewhat pro¬ 
visional extension of the outline presented in Chapter I. 


252 


ANIMAL ACTIVITIES. 


Man 



CCELENTERATA 

( Jelly-fish 

Coral-builders) 


Sponges 


Protozoa 


( Amasbae 
Mon era) 


Fig. 205. —A Genealogical Tree. 




ANIMAL RELATIONSHIPS . 


253 


PROTOZOA. 


'classes. 

Rhizopoda move by pseudopodia. Examples of 
this class are amoeba and chalk-animals. 

Infusoria move by cilia. Examples of this class 
are the bell animalcules and paramecium. There 
are other classes of Protozoa. 


PORIFERA. 


Keratose sponges have skeletons made of horn-like 
material. 

Calcareous sponges have skeletons composed of spic¬ 
ules of carbonate of lime. 

Silicious sponges have skeletons composed of 
quartz-like material, or of a combination of sili¬ 
cious spicules and silk-like fibres. 

These groups are not strictly classes. All sponges 
belong to the class Porifera. 


CCELENTER AT A. 


'CLASSES. 

Hydrozoa have the mouth at the top of a sort 
of proboscis. The entire body-cavity is a 
digestive cavity. Hydra, hydractinia, cam- 
panularia, sertularia, and many kinds of 
jelly-fish belong to this class. 

Scyphozoa are marine jelly-fishes. 

Actinozoa have the mouth-opening into a 
stomach-cavity distinct from the body-cav¬ 
ity. The body is also divided by radiating 
partitions. Sea-anemones and coral animals 
belong to this class. 

Ctenophora are transparent or nearly trans¬ 
parent comb-jellies. 


ECHINQPERMATA. 


CLASSES. 

Asteroidea are animals resembling the com¬ 
mon starfish. 

Ophiuroidea are animals resembling the 
sand-stars. 

Echinoidea are animals resembling sea- 
urchins. 

Crinoidea are stemmed forms. As fossils 
they occur in great abundance. They are 
known as stone-lilies. 

Other classes of Echinodermata are largely 
fossil forms. 


VERMES. 


No attempt is here made to give classes of Vermes. 
Instead of Vermes many authors now name several sub¬ 
kingdoms or phyla. Some of these are as follows: 
Platyhelminthes, or Flatworms. These are worms of 
low organization, including parasites like the liver- 
4 fluke and tapeworm. 

Nemathelminthes, Roundworms. These low forms 
have cylindrical bodies. The trichina belongs here. 
Rotifers , Polyzoa , and Brachiopoda have been vari¬ 
ously classed, often as members of the sub-kingdom 
Vermes. Their position is not fully settled. 








ARTHROPODA. 


2 54 


ANIMAL ACTIVITIES . 


CLASSES. 


Insecta. 


( Annulata. These are the more highly organized worms 
VERMES. ) like the earthworms and leeches. They are com- 
( monly regarded as a separate sub-kingdom or phylum. 
' Thysanura, spring-tails. 

Pseudo-neuroptera, dragon-fly. 

Orthoptera, grasshopper. 

Hemiptera, aphis. 

Neuroptera, ant-lion. 

Coleoptera, potato-beetle. 

Diptera, house-fly. 

Lepidoptera butterfly. 

Hymenoptera, bee 

! Spiders. 

Scorpions. 

Mites. 

j Centipedes 
] Millipedes. 

f Here belong the crayfish, lobster, shrimp, crab, 
J sand-hopper, pill-bug, asellus, cyclops, daphnia, 
I fish-lice, barnacles, and many other arthropoda 
[ which breathe by means of gills. 


Myriapoda. 


Crustacea. 


MOLLUSCA. 


CHORDATA. 


CLASSES. 

Pelecypoda, or bivalve mollusks, like clams, oysters, 
and scallops. 

Gastropoda, or univalve mollusks, like slugs and snails. 
Cephalopoda, including the squid, octopus, and nauti¬ 
lus. 

Amphineura, including the chitons. 

Omitting some low forms of somewhat doubtful re¬ 
lationship, we may call all animals belonging to this 
sub-kingdom Vertebrata and include them in classes as 
given below. 

CLASSES. 

Cyclostomi, including the lancelet or Amphioxus. 
Pisces, including all fishes. 

Amphibia, including frogs and their allies. 

Reptilia, including snakes and turtles. 

Aves, including birds. 

Mammalia, including the higher animals bearing hair 
or fur and provided with glands secreting milk. 
Man belongs to this class and to the order Primates, 
to which order the monkeys also belong. 


VOCABULARY. 


Am phi ox'us (Gr. amphi , on both 
sides), and oxys, sharp), a small 
fish-like vertebrate. It is also 
called the lancelet. 

An nu la'ta (Lat. annulus , a little 
ring), a division of Vermes in¬ 
cluding the common earth-worm. 


Archae op'te ryx (Gr. archaios , 
ancient, and pteryx , a wing), a 
fossil bird. 

A'ves (Lat. avis , a bird), birds. 

Di'a phragm (Gr. dia, through, 
and phragnymi , to enclose), a 
muscle characteristic of mam- 












ANIMAL RELATIONSHIPS. 


2 55 


mals, separating the thoracic and 
visceral cavities. 

Dig i ti grade (Lat. digitus , a fin¬ 
ger, 2L\\dgradus, a step), walking 
on the toes without using the 
sole of the foot. 

Gas'tru la (Lat. dim. of gaster , the 
belly), an embryonic iorm of 
animals belonging to the Meta¬ 
zoa. 

Mam'mal (Lat. mamma , breast), a 


vertebrate animal whose female 
has milk-producing glands. 

Mor'u la (Gr. moron , a mulberry), 
an early stage from the growth of 
an egg. 

Plan'ti grade (Lat. planta, the sole 
of the foot, and gradus , a step), 
applied to animals which walk 
on the sole of the foot. 

Pter o dac'tyl (Gr. pteron, a wing, 
and daktylos, a finger), an ex¬ 
tinct flying reptile. 































































♦ 






















INDEX. 


A 

Abdomen of Crustacea, 102 
“ “ grasshopper, 32 

“ il insects, 32 
Aboral surface, 140 
Acephala, 165 
Actinozoa, 137 
Activities of amoeba, 116 
11 “ bird, 199 

u “ butterfly, 47 
11 li earthworm, 150 

11 11 fresh-water mussel, 

158 

** “ frog, 181 

“ 11 grasshopper, 36 

“ “ hydra, 129 

“ “ spider, 93 

“ “ starfish, 142 

Adaptations, 86 
Adductor muscles, 156, 159 
Air-sacs of birds, 205 
“ “ spiders, 97 

Alimentary canal, 37 
Alternation of generations, 133 
Ambulacral areas, 141 
“ feet, 140 
Amoeba, 116 
Amphibia, 192 
Amphioxus, 247 
Ampullae, 141, 143 
Analogous organs, 106 
Anatomy, 30 
Angleworm, 148 
Animal kingdom, 2 
Animal relationships, 243 
Annulata, 148 

Anodon, 155, 157, 254 

Anosia plexippus, 68 
Antennae, 33 

“ of crayfish, 105 

<< “ grasshoppers, 33 


Antennules, 105 
Aorta of fish, 170 
“ “ frog, 195 

Apes, 232 
Aphis, 72 
Apparatus, 4 

Appendicular skeleton of frog, 189 

Aquaria, 8 

Arachnida, 113 

Archaeopteryx, 209 

Argonaut, 166 

Aristotle’s lantern, 146 

Arthropoda, 2, m 

Ascidians, 246 

Asellus, 86 

Assimilation, 118 

Asterias vulgaris, 140 

Atlas bone, 188 

Auditory nerves, 173 

Auricle of fish, 170 

Aves, 254 

Axial skeleton, 220 

“ “ of frog, 188 

B 

Balancer of fly, 58, 67 
Barnacles, no 
Barriers, 238 
Basipodite, 104, 107 
Bat, 222 
Batrachia, 192 
Bees, 89, 90 
Bilateral symmetry, 32 
Biology, 25 
Birds and insects, 200 
“ “ reptiles, 205 

Blood-corpuscles, 184 
Blue-bottle fly, 57 
Bluejay, 23 
Bones of fish, 173 
“ “ frog, 188 


257 



258 


INDEX. 


Botany, 31 

Branchial arches of fish, 170 
Bream, 14 
Breeding-cage, 6 
Brittle starfish, 144 
Butterflies, 5, 21, 45 
Butterfly enemies, 50 
Byssus, 167 

C 

Cabbage-butterfly, 49 

Caddis-fly and larva, 79 

Calcareous sponges, 125 

Campanularian hydroids, 14 

Carapace, 104 

Carbon, 28 

Carbon dioxid, 28 

Care of specimens, 17 

Care of young among birds, 202 

Carpus, 194, 204, 210 

Case insects, 12 

Cat, 211 

Caterpillars, 6, 48 
Catfish, 14 
Catocala, 52 

Causes of dispersals, 238 
Cecropia, 22 
Cell, 117 
Centipede, 98, 99 
Cephalopoda, 166 
Cephalothorax, 101 
Cerebellum, 173 
Cerebral lobes, 173 
Cerebrum, 173 
Chalk animals, 120 
Characteristics of actinozoa, 137 

“ “ amphibia, 192 

“ “ arachnida, 113 

“ “ birds, 205 

“ “ coelenterata, 137 

“ “ Crustacea, 113 

u “ echinodermata 

“ “ hydrozoa, 147 

u il mollusca, 166 

“ “ pisces, 175 

“ “ protozoa, 123 

“ “ reptilia, 192 

u “ scyphozoa, 137 

Chemistry of life, 24 
Chimpanzee, 182 
Chitin, 44 


Chordata, 2, 174, 254 
Chrysalids, 48 
Cilia, 121 

Circulation of birds, 201 

“ “ fish, 171 

“ “ frog, 185 

“ “ man, 221 

Classes, 112 

Classification of animal kingdom, 
2, 243, 253, 254, 
255 

“ “ arthropoda, hi 

“ ** birds, 207 

“ “ insecta, 64 

“ “ mammalia, 224 

Clavicle, 194 
Clitellum, 149, 151 
Cloaca, 201 
Cockroach, 20, 86 
Cocoons, 48 

Coelenterata, 2, 128, 129, 137, 253 

Coleoptera, 65 

Collecting, 4 

Colonies, 14, 132 

Colorado beetle, 60, 238 

Columbinse, 208 

Commenselism, 132 

Common crab, 2, 108 

Compound eye, 41 

Compounds, 27 

Condyle, 188, 210, 217, 219 

Contractile vacuole, 117 

Coracoid bones, 203 

Coral, 2, 135 

Cornea, 214 

Corpuscles, 184 

Costal, 56 

Coxa of insects, 34 

Coxopodite, 104, 107 

Crayfish, 2, 13, 101 

Cricket, 5, 41, 42 

Crinoids, 146 

Cross-fertilization, 131 

Crow, 23 

Crustacea, 101 

Ctenophora, 253 

Cyclops, 11, 109 

D 

Danais archippus, 68 
Daphnia pulex, 109 



INDEX. 


2 59 


Decomposition of water, 26 
Definitions: see vocabularies 
Degeneration, no 
Dental formulae, 212 
Derivations: see vocabularies 
Diaphragm, 223 
Differentiation, 131 
Digestion, 128 
Digitigrade feet, 228 
Diptera, 64 
Discovery, 30 
Dispersals, 237 
Dissection of grasshopper, 34 
Distribution of animals, 236, 250 
Ditycus, 80, 87 
Division of labor, 131 
Dragon-fly, 60, 76 
Duckweed, 9 

E 

Earthworm, 7, 148 
Echinodermata, 142 
Ectoderm, 123 
Eggs of birds, 201 
“ “ frogs, 23, 188 

Elements, 27 
Elytra, 67 
Embryology, 246 
Enamel, 231 
Endoderm, 123 
Endopodite, 104, 107 
English sparrow, 197 
Entomostraca, 109 
Epidermis of mammals, 229 
Eustachian tube of frog, 181 
Excretion, 30 
Exopodite, 104, 107 
Experiments, 25 

F 

Facets, 33 
Families, 112 
Fauna, 237 
Feathers, 198 
Feet of birds, 198 
Femur of insects, 34 
“ “ man, 194 

Fertilization of plants by insects, 89 
Fibula, 167 


Fingers and toes of mammals, 224 

Fins of fish, 159 

Fishes, 169 

Fission, 118 

Flies, 6, 57 

Flight of birds, 202, 203, 204 
“ “ insects, 42 

Food of amoeba, 118 
“ “ butterfly, 5, 49 

“ “ caterpillar, 6, 48 

“ “ crayfish, 13 

“ “ earthworm, 150 

“ “ fish, 169 

“ “ fly, 6, 57 

“ “ frog, 7, 179 

“ “ grasshopper, 36 

“ “ hydra, 11, 128, 129 

“ “ leech, 13 

“ “ mussel, 8, 166 

“ “ slug, 7 

“ “ snail, 8 

“ “ spider, 6, 94 

“ “ starfish, 142 

“ “ tadpole, 13 

“ “ turtle, 7 

“ “ wasp, 5 

Foot of horse, 228 
Foraminifera, 120 
Formaldehyde, 19 
Fossils, 244 

Fresh-water mussel, 155 
Frog, 7, 179 
Frogs’ eggs 23, 186 
Fungi, a, 136 

G 

Galaxea, 136 
Ganglion, 36 
Gastropoda, 165 
Gastrula, 249 
Genealogical tree, 252 
Genera, 112 

Geological distribution, 237, 241 
Gill arches, 170 
“ clefts, 170 
*• filaments, 170 
“ slits, 170 
Gorilla, 220 
Grallatores, 208 
Grasshopper, 5, 32 
Growth of lungs in frogs, 187 





26 o 


INDEX. 


H 

Habitat, 236, 240 
Habits and organs, 88 
Haemal arch, 174 
“ cavity, 174 
Hair, 229 

Hands and feet of mammals. 227 

Haustellate, 56 

Head of insect, 33 

Heart of frog, 183 

Hemiptera, 65 

Heredity, 250 

Hermaphrodite, 131 

Hermit-crab, 18 

Hinge ligament, 162 

Histology, 31 

Homologies, 107 

Homologous organs, 106 

Hoofs, 230 

Horns, 230 

Hornwort, 9 

House-fly, 5 

Humerus of frog, 189 

Hydra, 10, 128 

Hydractina, 131 

Hydrozoa, 13 7 

Hymenoptera, 66 

I 

Ichneumon-fly, 74 
Imago, 49 
Incisors, 212 
Infusoria, 121 

Inhalent pores of sponge, 124 
Insect adaptations, 86 
“ communities, 89 
Insects and plants, 91 
Interambulacral areas, 141 
“ plates, 141 

Isolated areas, 239 

J 

Jelly-fish, 154, 155 
K 

Kallima, 61 
Keel in birds, 205 
Keratose sponges, 125 


L 

Labium, 33 
Labrum, 33 
Lamellibranchiata, 165 
Lancelet, 247 
Larvae of butterflies, 48 
Lateral line, 169 
Leech, 13 

Lepidoptera, 45, 46 
Life, 24 

Life-histories, 68 
Limenitis Ursula, 53 
Lingual ribbon, 166 
Lithobius, 98 
Living matter, 24 
Lobster, 102 
Locust, 32 


M 

Madrepora, 136 
Madreporic body, 140 
Mammals, 217 
Mammalian skeleton, 218 
“ viscera, 223 
Mandibles, 33 

Mantle of mollusca, 156, 161, 166 

Mask of dragon-fly larva, 77 

Materials for study, 4 

Matter, 24 

Maxillae, 34 

Maxillipeds, 103 

May-flies, 80 

Medulla oblongata, 195 

Medusa, 134, 135 

Mesenteries of sea-anemone, 135 

Mesoglcea, 123 

Metamorphosis of insects, 47 

Microgaster-fly, 75 

Migration, 238 

Milkweed butterfly, 68, 237 

Mimicry, 53, 250 

Mollusca, 2, 165, 166 

Morula, 249 

Moths, 45 

Moulting, 39 

Mouth-parts of insects, 33, 34, 35 
Mud-wasp, 61 
Muscles of frog, 188 
Mussels, 8, 155 



INDEX. 


261 


N 

Names of insects, 66 
Natatores, 208 
Natural selection, 54 
Nauplius, hi 
N autilus, 166 
Nemathelminthes, 253 
Neuroptera, 65 
Nettling cells, 129 
Neural arch, 173 
“ cavity, 174 
“ spine, 174 
Nictitating membrane, 197 
Nitrogen, 27 
Notochord, 177 
Nucleus, 117 
Nutrition, 30 

“ of grasshopper, 37 

O 

Ocelli, 33 

Olfactory lobes of fish, 173 
Oosperms, 131 
Operculum of snail, 164 
Optic lobes of fish, 173 
Oral surface of starfish, 140 
Orders, 112 

“ of insects, 64 
Orthoptera, 65 
Oscula of sponge, 124 
Osmosis, 38 
Ovipositor, 33 
Oxidation, 27 

P 

Pallial line, 156 
Palpi, 34 
Paramecium, 122 
Parthenogenesis, 73 
Passeres, 208 
Pearls, 161 
Pectoral fins, 169 
Pectoral girdle, 175 
Pedal ganglia, 162 
Pedicellarise, 140 
Pelecypoda, 165 
Pelvic girdle, 175 
Peritoneum, 181 
Phalanges, 189, 199 
Phosphorescence, 114 


Phylum, 1, 2 
Physiology, 30 
Pisces, 175 
Plantigrade feet, 227 
Plant-lice: see Aphis 
Pleurum, 32 

Poison-fangs of spiders, 97 

Pol yp, 135 

Polyzoa, 253 
Pond-snail, 163 
Pond-weed, 9 
Porifera, 125, 254 
Preparation of specimens, 17 
Preservation of specimens, 19 
Primates, 254 
Proboscis of moth, 50 
Prolegs, 69 

Protection of birds, 200 
Protective coloring, 52 
Protopodite, 104, 107 
Protozoa, 116, 123 
Pseudoneuroptera, 65 
Pseudopodia, 119 
Pterodactyl, 245 
Pupation, 70 

R 

Radiate symmetry, 2 
Range of animals, 237 
Raptores, 208 
Reference-books, vi 
Repair, 26 
Reproduction, 30 

“ of amoeba, 118 

ft “ grasshopper, 37 

Reptilia, 192 
Resemblances, 61, m 
Respiration of grasshopper, 37 
Rhizopoda, 119 

S 

Sand-wasp, 74 
Sarcoda, 123 
Sauropsida, 207 
Scansores, 208 
Scyphozoa, 134, 137 
Sea-anemone, 15 
“ cucumber, 146 
“ squirt, 246 
“ urchin, 145 
Sedentary, 115 




262 


INDEX. 


Senses of grasshopper, 40 
Septa of coral, 135 
Serial homology, 107 
Shrimp, 101 
Silicious sponge, 125 
Siphon of mussel, 158 
Skeleton of bat, 222 
“ “ bird, 193 

“ “ chimpanzee, 223 

“ “ fish, 173 

“ “ frog, 193 

“ “ horse, 215 

“ “ man, 194 

Slugs, 7, 162 
Smelt, 169 
Snails, 5, 163 
Snakes, 7 
Somite, 104 
Sow-bug, 5 
Species, 112 
Sperms of hydra, 130 
Spicules of sponge, 125 
Spider, 93 

Spinal cord, 173, 174, 195 
Spinal nerve, 173 
Spinnerets, 94 
Spiracles, 32 
Sponges, 123 
Squash-bug, 61 
Squid, 166 
Starfish, 140 
Sternum, 104 
Stone-lilies, 2 
Stridulating, 41, 42 
Structure and habitat, 240 
Struthii, 207 
Stylets, 43 

Supraoesophageal ganglia, 167 
Survival of fittest, 35 
Swimmerets, 103 

Sympathetic system of nerves, 181 
Synapta, 146 

T 

Tadpoles, 179 
Tanning worms, 148 
Tarsus of insect, 34 
“ “ man, 197 

Teeth of mammals, 231 
Telson, 115 
Tergum, 32, 104 


Thecae, 138 
Thorax of insects, 33 
Thysaneura, 65 
Tibia of insect, 34 
“ “ man, 194 

Tongue of frog, 182 
Trachea of an insect, 38 
Trochanter of insects, 34 
Turtles, 7 
Tympanum, 33 

U 

Unio, 155 
Urostyle, 198 
Urea, 29 

Usefulness of earthworms, 153 
V 

Variation, 251 
Ventricle of fish, 170 
Vermes, 148 
Vertebrata, 174, 254 
Visceral cavity, 174 
Vocabularies of terms applied to 
one-celled animals and sponges, 
126 

coelenterata, 147 
Crustacea, 115 
echinodermata, 147 
insects, 44, 56, 67, 85 
mollusca, 167 

vertebrate animals, 176, 177, 
210, 255 

Vocabularies of general terms fre¬ 
quently used, 31, 100, 255 

W 

Wasps, 5 
Waste, 26 

Water-boatman, 80, 81 
“ fleas, 109 
“ spider, 95 
Web of spider, 95 
Wing of birds, 198 
“ insect, 42 
Winglet, 58 

Z 

Zooids, 132 
Zoology, 30 
























































































































• 





























































































































































































































































































































































